<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2025 Workiva-->
<!--r:9857d200-2034-4106-b6c4-e6d9d3e86809,g:2caf03e3-c2d4-4c80-be13-12724503b0fa-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.cinfin.com/role/CondensedConsolidatedStatementsofShareholdersEquity" xlink:type="simple" xlink:href="cinf-20250930.xsd#CondensedConsolidatedStatementsofShareholdersEquity"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/CondensedConsolidatedStatementsofShareholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_a7cf90c6-c9aa-4a15-9c8f-b118bb7a22c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StatementTable_a7cf90c6-c9aa-4a15-9c8f-b118bb7a22c3" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_776b915e-f8e9-49a8-b21a-e18ab597816a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_a7cf90c6-c9aa-4a15-9c8f-b118bb7a22c3" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_776b915e-f8e9-49a8-b21a-e18ab597816a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_776b915e-f8e9-49a8-b21a-e18ab597816a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_776b915e-f8e9-49a8-b21a-e18ab597816a" xlink:to="loc_us-gaap_EquityComponentDomain_776b915e-f8e9-49a8-b21a-e18ab597816a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_776b915e-f8e9-49a8-b21a-e18ab597816a" xlink:to="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_7b33d38b-1ffb-4ac0-af40-09ae325b345a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:to="loc_us-gaap_CommonStockMember_7b33d38b-1ffb-4ac0-af40-09ae325b345a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_05b0247d-d071-4539-9304-da70e4288d9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_05b0247d-d071-4539-9304-da70e4288d9d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_0027bf8e-c392-47a0-8f3f-7ea024bb9055" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:to="loc_us-gaap_RetainedEarningsMember_0027bf8e-c392-47a0-8f3f-7ea024bb9055" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_38cfc462-4438-42de-8263-36b6c5ce5ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_38cfc462-4438-42de-8263-36b6c5ce5ff3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockCommonMember_e7b8f19a-7917-4457-bf01-67c093fd1221" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockCommonMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_50de55d5-a538-4e29-8634-a8a3677aa68d" xlink:to="loc_us-gaap_TreasuryStockCommonMember_e7b8f19a-7917-4457-bf01-67c093fd1221" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5b98cb5b-6a2c-45db-b652-e03b000ce429" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StockholdersEquity_5b98cb5b-6a2c-45db-b652-e03b000ce429" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_95eb6243-061b-41a2-b051-1d56d4202b07" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_95eb6243-061b-41a2-b051-1d56d4202b07" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2036f2c6-c899-486a-a9d3-629ee9e289b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_2036f2c6-c899-486a-a9d3-629ee9e289b0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_a262e372-ef0d-4382-97f3-456bff2b3227" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StockholdersEquityOther_a262e372-ef0d-4382-97f3-456bff2b3227" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_779ef168-6f6e-4d0c-820b-f55e9b7d2394" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_NetIncomeLoss_779ef168-6f6e-4d0c-820b-f55e9b7d2394" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DividendsCommonStockCash_cd13a22a-6438-45c0-93ba-898f25c8a916" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DividendsCommonStockCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_DividendsCommonStockCash_cd13a22a-6438-45c0-93ba-898f25c8a916" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_7ee4cadd-58a0-4b32-ac4f-36cf5974684f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_7ee4cadd-58a0-4b32-ac4f-36cf5974684f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_758c64b2-93d9-447e-8272-ad67a33a797c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockValueAcquiredCostMethod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_TreasuryStockValueAcquiredCostMethod_758c64b2-93d9-447e-8272-ad67a33a797c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SharesAcquiredDuringPeriodValueEmployeeShareBasedCompensationPlans_6ca91339-d56c-4117-b923-e53b3e61d36d" xlink:href="cinf-20250930.xsd#cinf_SharesAcquiredDuringPeriodValueEmployeeShareBasedCompensationPlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_cinf_SharesAcquiredDuringPeriodValueEmployeeShareBasedCompensationPlans_6ca91339-d56c-4117-b923-e53b3e61d36d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_d50613e2-2735-4ea8-8149-6a5be56b1934" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_a45428bd-4ea0-45e3-8b1e-20c4c8c884ad" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_a45428bd-4ea0-45e3-8b1e-20c4c8c884ad" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2bd249c3-30fc-4474-8fb7-9cdb9555c11f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_2bd249c3-30fc-4474-8fb7-9cdb9555c11f" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TreasuryStockSharesAcquired_88c81382-0cae-4a39-96a4-1d560b8d3915" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TreasuryStockSharesAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_TreasuryStockSharesAcquired_88c81382-0cae-4a39-96a4-1d560b8d3915" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SharesAcquiredDuringPeriodEmployeeShareBasedCompensationPlansShares_02f51f9a-33a1-4bb2-aefa-03a9d7377040" xlink:href="cinf-20250930.xsd#cinf_SharesAcquiredDuringPeriodEmployeeShareBasedCompensationPlansShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_cinf_SharesAcquiredDuringPeriodEmployeeShareBasedCompensationPlansShares_02f51f9a-33a1-4bb2-aefa-03a9d7377040" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesOther_5b5dd31e-8a1c-440d-8de5-4cdf0599cf29" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesOther_5b5dd31e-8a1c-440d-8de5-4cdf0599cf29" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_07167554-280b-462d-b310-017d68e460d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockDividendsPerShareDeclared_49d91466-25fc-4f58-a79a-33a1ccc30a96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockDividendsPerShareDeclared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_bff20c34-7168-45aa-bf08-05a2f36f8814" xlink:to="loc_us-gaap_CommonStockDividendsPerShareDeclared_49d91466-25fc-4f58-a79a-33a1ccc30a96" xlink:type="arc" order="16"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/InvestmentsAnalysisofCostorAmortizedCostGrossUnrealizedGainsandLossesandFairValueforInvestmentsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#InvestmentsAnalysisofCostorAmortizedCostGrossUnrealizedGainsandLossesandFairValueforInvestmentsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/InvestmentsAnalysisofCostorAmortizedCostGrossUnrealizedGainsandLossesandFairValueforInvestmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_23c33aab-6d5c-43da-8f42-64f9ed81947f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_23c33aab-6d5c-43da-8f42-64f9ed81947f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_855c8f29-14ec-4317-ade2-4d34bb9f596c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleTable_23c33aab-6d5c-43da-8f42-64f9ed81947f" xlink:to="loc_us-gaap_FinancialInstrumentAxis_855c8f29-14ec-4317-ade2-4d34bb9f596c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_855c8f29-14ec-4317-ade2-4d34bb9f596c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_855c8f29-14ec-4317-ade2-4d34bb9f596c" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_855c8f29-14ec-4317-ade2-4d34bb9f596c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_855c8f29-14ec-4317-ade2-4d34bb9f596c" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_05589405-5848-4827-8c85-1469ee35d010" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_05589405-5848-4827-8c85-1469ee35d010" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_5e86c29a-5a0d-4f36-b529-1eb5e7db7a30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_5e86c29a-5a0d-4f36-b529-1eb5e7db7a30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_17020fab-aadd-4a56-ae92-8a7706770be0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_17020fab-aadd-4a56-ae92-8a7706770be0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_c07fc0d6-5c79-4084-919a-50f241fa58cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_c07fc0d6-5c79-4084-919a-50f241fa58cd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_4b5a003c-2dc0-44e0-b1ce-1a830fbb8a6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_4b5a003c-2dc0-44e0-b1ce-1a830fbb8a6f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_f7fdbb30-f60f-4ae2-98a1-58c1784524a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_09eb3995-e89b-4dfe-8c7c-1b370fa30c02" xlink:to="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_f7fdbb30-f60f-4ae2-98a1-58c1784524a7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleAmortizedCostBasis_f19a27b9-f2bb-453a-ae10-2671464d3492" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_InvestmentsAvailableForSaleAmortizedCostBasis_f19a27b9-f2bb-453a-ae10-2671464d3492" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax_1f3b9535-de5f-4a09-99b1-4549a81221d4" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax_1f3b9535-de5f-4a09-99b1-4549a81221d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax_656a47ff-671d-477a-8aef-48c71db83935" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_InvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax_656a47ff-671d-477a-8aef-48c71db83935" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSale_e3c325d9-4112-4b85-a3a8-1acbcde961aa" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_InvestmentsAvailableForSale_e3c325d9-4112-4b85-a3a8-1acbcde961aa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleAmortizedCostBasis_256b7fc1-a4e9-45b8-a68a-b438f8b7d579" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleAmortizedCostBasis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleAmortizedCostBasis_256b7fc1-a4e9-45b8-a68a-b438f8b7d579" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax_bdc7fa1f-2f22-4fa9-ba62-4b8e7f2724a1" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedGainBeforeTax_bdc7fa1f-2f22-4fa9-ba62-4b8e7f2724a1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax_b04da6f2-7f6c-4bec-8c18-5fdfa70d6877" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleAccumulatedGrossUnrealizedLossBeforeTax_b04da6f2-7f6c-4bec-8c18-5fdfa70d6877" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_189227bc-532e-4a6e-9559-07c869d20948" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_ShortTermInvestments_189227bc-532e-4a6e-9559-07c869d20948" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss_354e34a6-40b0-41d8-8d83-4b0c63408476" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleAmortizedCostAfterAllowanceForCreditLoss_354e34a6-40b0-41d8-8d83-4b0c63408476" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_cd4dd347-fada-4092-93dc-b38c1ebdfd6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax_cd4dd347-fada-4092-93dc-b38c1ebdfd6e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_59c10185-cfe4-4cd4-939c-3d1251ccb66f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_59c10185-cfe4-4cd4-939c-3d1251ccb66f" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5a328843-0fb4-430f-be1e-a59ec655a366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfAvailableForSaleSecuritiesLineItems_356efa83-4d72-49e9-91a0-83a043c1b27f" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_5a328843-0fb4-430f-be1e-a59ec655a366" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/InvestmentsFairValuesandUnrealizedLossesbyInvestmentCategoryandbyDurationofSecuritiesContinuousUnrealizedLossPositionDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#InvestmentsFairValuesandUnrealizedLossesbyInvestmentCategoryandbyDurationofSecuritiesContinuousUnrealizedLossPositionDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/InvestmentsFairValuesandUnrealizedLossesbyInvestmentCategoryandbyDurationofSecuritiesContinuousUnrealizedLossPositionDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_e220a831-2e08-4d64-8940-6a69e9d2ed0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_e220a831-2e08-4d64-8940-6a69e9d2ed0d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeAxis_51eb61fc-5335-438b-98ac-5c1cb5c023e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_e220a831-2e08-4d64-8940-6a69e9d2ed0d" xlink:to="loc_us-gaap_InvestmentTypeAxis_51eb61fc-5335-438b-98ac-5c1cb5c023e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_51eb61fc-5335-438b-98ac-5c1cb5c023e9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_51eb61fc-5335-438b-98ac-5c1cb5c023e9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_51eb61fc-5335-438b-98ac-5c1cb5c023e9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_852fe162-57bc-4a99-bcd5-9d39a5352f3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_51eb61fc-5335-438b-98ac-5c1cb5c023e9" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_852fe162-57bc-4a99-bcd5-9d39a5352f3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesMember_5807d167-39f1-461d-bda7-5ab4c68602b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_852fe162-57bc-4a99-bcd5-9d39a5352f3d" xlink:to="loc_us-gaap_DebtSecuritiesMember_5807d167-39f1-461d-bda7-5ab4c68602b7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionFairValueTable_e220a831-2e08-4d64-8940-6a69e9d2ed0d" xlink:to="loc_us-gaap_FinancialInstrumentAxis_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_60eeb0bb-ae01-4076-bd07-4b5f3b70a9c1" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_192454d9-f473-4363-86a6-adbff55e6598" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_192454d9-f473-4363-86a6-adbff55e6598" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_ce438cc6-e1de-498d-aa5b-aec236fa78ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_ce438cc6-e1de-498d-aa5b-aec236fa78ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_7cd7d4ab-2664-4f66-a855-bc7c840382d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_7cd7d4ab-2664-4f66-a855-bc7c840382d4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_c2e56256-863e-409c-9d69-6468b3426829" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_c2e56256-863e-409c-9d69-6468b3426829" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_50951505-5293-4149-9482-4aaebe10fba3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_50951505-5293-4149-9482-4aaebe10fba3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_c87fe530-2160-4fbe-9dde-9158bffb0934" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_b430b7db-3e03-4496-b13a-5ea23be00a7a" xlink:to="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_c87fe530-2160-4fbe-9dde-9158bffb0934" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_437681b4-2a05-4ce9-bbd9-3f9c7d545ac3" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_437681b4-2a05-4ce9-bbd9-3f9c7d545ac3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_c03a2dc0-6759-4c6a-b81f-43cc28b4a4f5" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_c03a2dc0-6759-4c6a-b81f-43cc28b4a4f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_73b032c1-e80c-4198-b98b-80ea89f3a9f2" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_73b032c1-e80c-4198-b98b-80ea89f3a9f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_4e77ba64-9093-4803-b89b-e30d7fd804c2" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_4e77ba64-9093-4803-b89b-e30d7fd804c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleUnrealizedLossPosition_2da6bd7b-b711-41a5-8737-deebf4e46d3e" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleUnrealizedLossPosition_2da6bd7b-b711-41a5-8737-deebf4e46d3e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss_07e54621-70d5-4b35-9031-74eda425d2bd" xlink:href="cinf-20250930.xsd#cinf_InvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_InvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss_07e54621-70d5-4b35-9031-74eda425d2bd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_123f6b10-6aa9-4fe4-ad1e-d73c12928bc4" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_123f6b10-6aa9-4fe4-ad1e-d73c12928bc4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_1ee8a788-34db-494e-b606-d862ca2c22ab" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_1ee8a788-34db-494e-b606-d862ca2c22ab" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_b2c6e49a-09cc-4844-9544-09b7dfa3d109" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_b2c6e49a-09cc-4844-9544-09b7dfa3d109" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_c35ed993-7d3e-48be-b9c0-c805b3e532d1" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_c35ed993-7d3e-48be-b9c0-c805b3e532d1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionTotal_24691f62-6102-4a01-9fc1-403e4f6a592e" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionTotal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionTotal_24691f62-6102-4a01-9fc1-403e4f6a592e" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss_a6141a26-0cf2-4d35-b96c-323f4db00103" xlink:href="cinf-20250930.xsd#cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_cinf_ShortTermInvestmentsAvailableForSaleUnrealizedLossPositionAccumulatedLoss_a6141a26-0cf2-4d35-b96c-323f4db00103" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_2a99b7af-62cc-4fd4-9383-1dc4cbe00eaf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months_2a99b7af-62cc-4fd4-9383-1dc4cbe00eaf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_a6f4236f-2be6-42ce-82d2-440539bb9fcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss_a6f4236f-2be6-42ce-82d2-440539bb9fcf" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_1a250663-628b-45c4-b2f2-46e875dbc17e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger_1a250663-628b-45c4-b2f2-46e875dbc17e" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_376e54c2-af75-49de-9679-d2afc106647d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss_376e54c2-af75-49de-9679-d2afc106647d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_ca199d0b-0b36-40f1-b234-55d1a3c43894" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPosition_ca199d0b-0b36-40f1-b234-55d1a3c43894" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_ec7a7934-f8e4-496f-bad1-3e2bdd6d7249" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValueAbstract_a71e67b9-f794-43b2-a581-58db3dcc5821" xlink:to="loc_us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax_ec7a7934-f8e4-496f-bad1-3e2bdd6d7249" xlink:type="arc" order="17"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/InvestmentsRealizedInvestmentGainsandLossesandChangeinUnrealizedInvestmentGainsandLossesandOtherItemsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#InvestmentsRealizedInvestmentGainsandLossesandChangeinUnrealizedInvestmentGainsandLossesandOtherItemsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/InvestmentsRealizedInvestmentGainsandLossesandChangeinUnrealizedInvestmentGainsandLossesandOtherItemsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems_65bccb84-d1cc-4fc7-a729-d67dd8b1ed47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGainLossOnInvestmentsTable_4584d1cb-370b-4da3-9903-7f30d86e3566" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfGainLossOnInvestmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems_65bccb84-d1cc-4fc7-a729-d67dd8b1ed47" xlink:to="loc_us-gaap_ScheduleOfGainLossOnInvestmentsTable_4584d1cb-370b-4da3-9903-7f30d86e3566" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeAxis_cad025c8-9381-4f8d-a273-3707bb16e329" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGainLossOnInvestmentsTable_4584d1cb-370b-4da3-9903-7f30d86e3566" xlink:to="loc_us-gaap_InvestmentTypeAxis_cad025c8-9381-4f8d-a273-3707bb16e329" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_cad025c8-9381-4f8d-a273-3707bb16e329_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_cad025c8-9381-4f8d-a273-3707bb16e329" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_cad025c8-9381-4f8d-a273-3707bb16e329_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_628d88be-0391-4fb5-9bee-11aaef403ff3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_cad025c8-9381-4f8d-a273-3707bb16e329" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_628d88be-0391-4fb5-9bee-11aaef403ff3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_4e20c8a3-668f-45dc-b0e9-8017aa3e20d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_628d88be-0391-4fb5-9bee-11aaef403ff3" xlink:to="loc_us-gaap_EquitySecuritiesMember_4e20c8a3-668f-45dc-b0e9-8017aa3e20d7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesMember_2bf90aad-d24b-4ae6-abcd-e3d88103e2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_628d88be-0391-4fb5-9bee-11aaef403ff3" xlink:to="loc_us-gaap_DebtSecuritiesMember_2bf90aad-d24b-4ae6-abcd-e3d88103e2eb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncomeAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems_65bccb84-d1cc-4fc7-a729-d67dd8b1ed47" xlink:to="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_0a42e401-8ba2-443f-a331-2e25c7d5ae49" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_us-gaap_InvestmentIncomeInterest_0a42e401-8ba2-443f-a331-2e25c7d5ae49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeDividend_ad938d76-60f3-4847-9d61-7f0b656829e5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeDividend"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_us-gaap_InvestmentIncomeDividend_ad938d76-60f3-4847-9d61-7f0b656829e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentIncomeOtherLongTermInvestments_d1c79f72-3aba-4042-965d-2085ed7088f3" xlink:href="cinf-20250930.xsd#cinf_InvestmentIncomeOtherLongTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_cinf_InvestmentIncomeOtherLongTermInvestments_d1c79f72-3aba-4042-965d-2085ed7088f3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GrossInvestmentIncomeOperating_59a09731-00cc-4f62-9ff1-53157312e9b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GrossInvestmentIncomeOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_us-gaap_GrossInvestmentIncomeOperating_59a09731-00cc-4f62-9ff1-53157312e9b0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInvestmentExpense_620dbaac-fb70-44fb-95ba-33af02b37f2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInvestmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_us-gaap_InvestmentIncomeInvestmentExpense_620dbaac-fb70-44fb-95ba-33af02b37f2d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_101b86fc-7ec9-48f9-81b2-b953059b0a77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetInvestmentIncomeAbstract_41995cab-f322-4bdc-8163-b9aa3f3b7123" xlink:to="loc_us-gaap_NetInvestmentIncome_101b86fc-7ec9-48f9-81b2-b953059b0a77" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestmentsAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ScheduleOfGainLossOnInvestmentsIncludingMarketableSecuritiesAndInvestmentsHeldAtCostIncomeStatementReportedAmountsSummaryLineItems_65bccb84-d1cc-4fc7-a729-d67dd8b1ed47" xlink:to="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RealizedInvestmentGainsLosses_8220cd35-abcb-422d-ae6e-3c1ebfd2f30c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RealizedInvestmentGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_us-gaap_RealizedInvestmentGainsLosses_8220cd35-abcb-422d-ae6e-3c1ebfd2f30c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnInvestments_0b3b975c-ea2c-470f-ba9b-b3f4c9cffdc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnrealizedGainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_us-gaap_UnrealizedGainLossOnInvestments_0b3b975c-ea2c-470f-ba9b-b3f4c9cffdc7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_afbaa5ab-4681-4aa8-8f2e-ba2902ffff9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedGain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedGain_afbaa5ab-4681-4aa8-8f2e-ba2902ffff9c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_51617117-59ec-4d1e-a449-5920a8be129c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_us-gaap_DebtSecuritiesAvailableForSaleRealizedLoss_51617117-59ec-4d1e-a449-5920a8be129c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ChangesInAllowanceForCreditLossesDuringPeriod_9f021ea5-2e69-461a-88cb-68a3b07413f6" xlink:href="cinf-20250930.xsd#cinf_ChangesInAllowanceForCreditLossesDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_cinf_ChangesInAllowanceForCreditLossesDuringPeriod_9f021ea5-2e69-461a-88cb-68a3b07413f6" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherRealizedInvestmentGainsLossesNet_e21887aa-eb01-4ae6-8a95-90ed09c971a6" xlink:href="cinf-20250930.xsd#cinf_OtherRealizedInvestmentGainsLossesNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_cinf_OtherRealizedInvestmentGainsLossesNet_e21887aa-eb01-4ae6-8a95-90ed09c971a6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_ed51347b-ba55-46f0-9b71-eee960112c67" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GainLossOnInvestmentsAbstract_60fbd34b-da81-4cfa-9ddc-7e5e7567f16d" xlink:to="loc_us-gaap_GainLossOnInvestments_ed51347b-ba55-46f0-9b71-eee960112c67" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/FairValueMeasurementsFairValueHierarchyforAssetsMeasuredatFairValueonRecurringBasisDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#FairValueMeasurementsFairValueHierarchyforAssetsMeasuredatFairValueonRecurringBasisDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/FairValueMeasurementsFairValueHierarchyforAssetsMeasuredatFairValueonRecurringBasisDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable_695689c4-ae71-4055-909b-caeb629401c8" xlink:href="cinf-20250930.xsd#cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable_695689c4-ae71-4055-909b-caeb629401c8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeAxis_20978fc3-3a4d-4054-923e-745217fd36c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable_695689c4-ae71-4055-909b-caeb629401c8" xlink:to="loc_us-gaap_InvestmentTypeAxis_20978fc3-3a4d-4054-923e-745217fd36c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_20978fc3-3a4d-4054-923e-745217fd36c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_InvestmentTypeAxis_20978fc3-3a4d-4054-923e-745217fd36c6" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_20978fc3-3a4d-4054-923e-745217fd36c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentTypeCategorizationMember_a96d1ad1-475a-491d-b913-2a3aad2f2088" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentTypeCategorizationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_InvestmentTypeAxis_20978fc3-3a4d-4054-923e-745217fd36c6" xlink:to="loc_us-gaap_InvestmentTypeCategorizationMember_a96d1ad1-475a-491d-b913-2a3aad2f2088" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesMember_4dee524e-8f52-4bf4-a2be-9d768709a0b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_a96d1ad1-475a-491d-b913-2a3aad2f2088" xlink:to="loc_us-gaap_EquitySecuritiesMember_4dee524e-8f52-4bf4-a2be-9d768709a0b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_TaxableFixedMaturitiesMember_ea62f782-b9b0-4f5d-ad3d-4b635cedbe1d" xlink:href="cinf-20250930.xsd#cinf_TaxableFixedMaturitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InvestmentTypeCategorizationMember_a96d1ad1-475a-491d-b913-2a3aad2f2088" xlink:to="loc_cinf_TaxableFixedMaturitiesMember_ea62f782-b9b0-4f5d-ad3d-4b635cedbe1d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_83a26152-8b23-4d21-9986-aefb1717b93f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable_695689c4-ae71-4055-909b-caeb629401c8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_83a26152-8b23-4d21-9986-aefb1717b93f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_83a26152-8b23-4d21-9986-aefb1717b93f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_83a26152-8b23-4d21-9986-aefb1717b93f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_83a26152-8b23-4d21-9986-aefb1717b93f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf7cf3a6-27f1-492e-9801-145e225ead6f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_83a26152-8b23-4d21-9986-aefb1717b93f" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf7cf3a6-27f1-492e-9801-145e225ead6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_206b9acc-ee0c-46f4-809a-a15e1f4d8a6c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf7cf3a6-27f1-492e-9801-145e225ead6f" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_206b9acc-ee0c-46f4-809a-a15e1f4d8a6c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_f37fe025-40b8-4707-be6b-ef4fbe638a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf7cf3a6-27f1-492e-9801-145e225ead6f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_f37fe025-40b8-4707-be6b-ef4fbe638a8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_1881dcdf-e0ca-4153-999c-d3540eab6bcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_bf7cf3a6-27f1-492e-9801-145e225ead6f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_1881dcdf-e0ca-4153-999c-d3540eab6bcf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinancialInstrumentAxis_a6e98aa2-492d-4721-8ca0-e477bfc994c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinancialInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_FairValueAssetsAndLiabilitiesMeasuredOnRecurringBasisTable_695689c4-ae71-4055-909b-caeb629401c8" xlink:to="loc_us-gaap_FinancialInstrumentAxis_a6e98aa2-492d-4721-8ca0-e477bfc994c6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a6e98aa2-492d-4721-8ca0-e477bfc994c6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a6e98aa2-492d-4721-8ca0-e477bfc994c6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_a6e98aa2-492d-4721-8ca0-e477bfc994c6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FinancialInstrumentAxis_a6e98aa2-492d-4721-8ca0-e477bfc994c6" xlink:to="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateBondSecuritiesMember_8fc39250-0462-430d-a968-e583efac0b0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateBondSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_CorporateBondSecuritiesMember_8fc39250-0462-430d-a968-e583efac0b0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_9104842d-a217-4eb1-b1c3-e3b1619d291f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USStatesAndPoliticalSubdivisionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_USStatesAndPoliticalSubdivisionsMember_9104842d-a217-4eb1-b1c3-e3b1619d291f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_3213208e-1833-4de7-a8ee-699be57487a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_USGovernmentSponsoredEnterprisesDebtSecuritiesMember_3213208e-1833-4de7-a8ee-699be57487a5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_86b560e1-05ee-4894-81d2-0633ba268301" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommercialMortgageBackedSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_CommercialMortgageBackedSecuritiesMember_86b560e1-05ee-4894-81d2-0633ba268301" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6ffcc1d5-9f66-4a6d-a8a5-ec327b40650b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_USGovernmentAgenciesDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_USGovernmentAgenciesDebtSecuritiesMember_6ffcc1d5-9f66-4a6d-a8a5-ec327b40650b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_b785b9ec-f0ef-4f74-b9db-e567cc69f808" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignGovernmentDebtSecuritiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_ForeignGovernmentDebtSecuritiesMember_b785b9ec-f0ef-4f74-b9db-e567cc69f808" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_a71a7452-c9ad-4ff6-95d2-c605c90cec03" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_CommonStockMember_a71a7452-c9ad-4ff6-95d2-c605c90cec03" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockMember_bcac70aa-961d-4bfb-a9e8-a16efefbdc8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PreferredStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_us-gaap_PreferredStockMember_bcac70aa-961d-4bfb-a9e8-a16efefbdc8e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_TaxableFixedMaturitiesMember_53d129da-eae4-415d-936e-02cf24a26050" xlink:href="cinf-20250930.xsd#cinf_TaxableFixedMaturitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TransfersAndServicingOfFinancialInstrumentsTypesOfFinancialInstrumentsDomain_8efbff5b-8498-4011-a15c-1c573fadef74" xlink:to="loc_cinf_TaxableFixedMaturitiesMember_53d129da-eae4-415d-936e-02cf24a26050" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_81dc3f35-f5f8-4eb8-8a2f-3341dc0863bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AvailableForSaleSecuritiesDebtSecurities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_us-gaap_AvailableForSaleSecuritiesDebtSecurities_81dc3f35-f5f8-4eb8-8a2f-3341dc0863bb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentsFairValueDisclosure_a0e37532-a9a6-4589-969a-2271fe1735e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_us-gaap_InvestmentsFairValueDisclosure_a0e37532-a9a6-4589-969a-2271fe1735e1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountAssets_3f7dfd87-e583-46e0-940b-9a5b3d177e95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_us-gaap_SeparateAccountAssets_3f7dfd87-e583-46e0-940b-9a5b3d177e95" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermInvestments_6a0583d7-7f5e-43d6-a6f3-d69d1635cd8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShortTermInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_us-gaap_ShortTermInvestments_6a0583d7-7f5e-43d6-a6f3-d69d1635cd8c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherInvestmentNotReadilyMarketableFairValue_4788e461-afda-4748-8d7d-4efa4f105173" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherInvestmentNotReadilyMarketableFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_746d47bb-418f-4352-b9f3-c9d702650340" xlink:to="loc_us-gaap_OtherInvestmentNotReadilyMarketableFairValue_4788e461-afda-4748-8d7d-4efa4f105173" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#FairValueMeasurementsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/FairValueMeasurementsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_33d40502-8b50-4b61-8c9e-cf6a518ec2ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fd1c0842-4066-440a-80df-747fa5490fb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_33d40502-8b50-4b61-8c9e-cf6a518ec2ae" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fd1c0842-4066-440a-80df-747fa5490fb6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_37697edd-6fc4-45af-9f41-bc9f9d3e091a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fd1c0842-4066-440a-80df-747fa5490fb6" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_37697edd-6fc4-45af-9f41-bc9f9d3e091a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_37697edd-6fc4-45af-9f41-bc9f9d3e091a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_37697edd-6fc4-45af-9f41-bc9f9d3e091a" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_37697edd-6fc4-45af-9f41-bc9f9d3e091a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_8800e509-3236-4408-85f3-6ebef3b7251c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_37697edd-6fc4-45af-9f41-bc9f9d3e091a" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_8800e509-3236-4408-85f3-6ebef3b7251c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentcontractreservesMember_80e3fcb8-8546-4734-b99d-87dc7ba6bd9d" xlink:href="cinf-20250930.xsd#cinf_InvestmentcontractreservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_8800e509-3236-4408-85f3-6ebef3b7251c" xlink:to="loc_cinf_InvestmentcontractreservesMember_80e3fcb8-8546-4734-b99d-87dc7ba6bd9d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_7b81a9de-f076-4169-b25f-793e278afc22" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_fd1c0842-4066-440a-80df-747fa5490fb6" xlink:to="loc_srt_ProductOrServiceAxis_7b81a9de-f076-4169-b25f-793e278afc22" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_7b81a9de-f076-4169-b25f-793e278afc22_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_7b81a9de-f076-4169-b25f-793e278afc22" xlink:to="loc_srt_ProductsAndServicesDomain_7b81a9de-f076-4169-b25f-793e278afc22_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_cd66ab8d-0060-4e3b-8416-a31b6c14a17f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_7b81a9de-f076-4169-b25f-793e278afc22" xlink:to="loc_srt_ProductsAndServicesDomain_cd66ab8d-0060-4e3b-8416-a31b6c14a17f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFixedAnnuityMember_8e82970c-b76c-45e4-9b8d-41b5b0d1d112" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_cd66ab8d-0060-4e3b-8416-a31b6c14a17f" xlink:to="loc_us-gaap_DeferredFixedAnnuityMember_8e82970c-b76c-45e4-9b8d-41b5b0d1d112" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StructuredSettlementAnnuityMember_313e2f56-41e9-411c-a6ed-96972cc887fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StructuredSettlementAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_cd66ab8d-0060-4e3b-8416-a31b6c14a17f" xlink:to="loc_us-gaap_StructuredSettlementAnnuityMember_313e2f56-41e9-411c-a6ed-96972cc887fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_85b2d2ed-6ca6-4432-a8ac-f973ec46fef5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_33d40502-8b50-4b61-8c9e-cf6a518ec2ae" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_85b2d2ed-6ca6-4432-a8ac-f973ec46fef5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OutstandingPrincipleAndInterestForLifePolicyLoans_b1de8a35-3839-498d-8281-c93b28015934" xlink:href="cinf-20250930.xsd#cinf_OutstandingPrincipleAndInterestForLifePolicyLoans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_33d40502-8b50-4b61-8c9e-cf6a518ec2ae" xlink:to="loc_cinf_OutstandingPrincipleAndInterestForLifePolicyLoans_b1de8a35-3839-498d-8281-c93b28015934" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefits_3fc853a0-05c2-4c99-943e-bdd38b54cdb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_33d40502-8b50-4b61-8c9e-cf6a518ec2ae" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefits_3fc853a0-05c2-4c99-943e-bdd38b54cdb4" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/FairValueMeasurementsSummaryofBookValueandPrincipalAmountsofLongTermDebtDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#FairValueMeasurementsSummaryofBookValueandPrincipalAmountsofLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/FairValueMeasurementsSummaryofBookValueandPrincipalAmountsofLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_5690391a-3641-40c1-83bb-e139902c01b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:to="loc_us-gaap_DebtInstrumentTable_5690391a-3641-40c1-83bb-e139902c01b1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_01d7cb69-e536-4670-9049-877aa0659740" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_5690391a-3641-40c1-83bb-e139902c01b1" xlink:to="loc_us-gaap_DebtInstrumentAxis_01d7cb69-e536-4670-9049-877aa0659740" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_01d7cb69-e536-4670-9049-877aa0659740_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_01d7cb69-e536-4670-9049-877aa0659740" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_01d7cb69-e536-4670-9049-877aa0659740_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_32d86966-3c80-4b82-b9ca-46547067a4a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_01d7cb69-e536-4670-9049-877aa0659740" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_32d86966-3c80-4b82-b9ca-46547067a4a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorDebenturesSixPointNinePercentDueTwentyTwentyEightMember_67b9234e-06cd-474f-b927-15f0d8b17e90" xlink:href="cinf-20250930.xsd#cinf_SeniorDebenturesSixPointNinePercentDueTwentyTwentyEightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_32d86966-3c80-4b82-b9ca-46547067a4a7" xlink:to="loc_cinf_SeniorDebenturesSixPointNinePercentDueTwentyTwentyEightMember_67b9234e-06cd-474f-b927-15f0d8b17e90" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorDebenturesSixPointNineTwoPercentDueTwentyTwentyEightMember_bb3644ab-f5fb-4e77-b0e2-2abda236e3b5" xlink:href="cinf-20250930.xsd#cinf_SeniorDebenturesSixPointNineTwoPercentDueTwentyTwentyEightMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_32d86966-3c80-4b82-b9ca-46547067a4a7" xlink:to="loc_cinf_SeniorDebenturesSixPointNineTwoPercentDueTwentyTwentyEightMember_bb3644ab-f5fb-4e77-b0e2-2abda236e3b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorNotesSixPointOneTwoFivePercentDueTwentyThirtyFourMember_d69b2413-a386-4dd6-9635-8b693d231c6e" xlink:href="cinf-20250930.xsd#cinf_SeniorNotesSixPointOneTwoFivePercentDueTwentyThirtyFourMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_32d86966-3c80-4b82-b9ca-46547067a4a7" xlink:to="loc_cinf_SeniorNotesSixPointOneTwoFivePercentDueTwentyThirtyFourMember_d69b2413-a386-4dd6-9635-8b693d231c6e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_2b47ac87-a81f-42a1-b3d5-9f13d446cff2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_2b47ac87-a81f-42a1-b3d5-9f13d446cff2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_DebtInstrumentIssuanceYear_e7b0885b-245d-464a-99ba-2b7f7c533acd" xlink:href="cinf-20250930.xsd#cinf_DebtInstrumentIssuanceYear"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:to="loc_cinf_DebtInstrumentIssuanceYear_e7b0885b-245d-464a-99ba-2b7f7c533acd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_c46e8309-f80e-4555-aeaf-950ee7046e72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:to="loc_us-gaap_LongTermDebt_c46e8309-f80e-4555-aeaf-950ee7046e72" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_fb1258f7-9277-4712-994a-297f75693475" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_9ad6e154-a6f4-41c7-b83e-92d52aaece8e" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_fb1258f7-9277-4712-994a-297f75693475" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/FairValueMeasurementsFairValuesofNotePayableandLongTermDebtDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#FairValueMeasurementsFairValuesofNotePayableandLongTermDebtDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/FairValueMeasurementsFairValuesofNotePayableandLongTermDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_25173aa9-cfb4-4167-bab4-70b6a6b52e93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_25173aa9-cfb4-4167-bab4-70b6a6b52e93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ae25acb-dddc-4e11-ab98-af74f806b741" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_25173aa9-cfb4-4167-bab4-70b6a6b52e93" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ae25acb-dddc-4e11-ab98-af74f806b741" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7ae25acb-dddc-4e11-ab98-af74f806b741_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ae25acb-dddc-4e11-ab98-af74f806b741" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_7ae25acb-dddc-4e11-ab98-af74f806b741_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ab01e4ca-9aa6-49a8-b083-79db7e933dab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_7ae25acb-dddc-4e11-ab98-af74f806b741" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ab01e4ca-9aa6-49a8-b083-79db7e933dab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_9dbf7c86-ca49-42be-9050-fefd168c07c3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ab01e4ca-9aa6-49a8-b083-79db7e933dab" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_9dbf7c86-ca49-42be-9050-fefd168c07c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_e7c76fac-a7a0-458b-88ba-00bb64ca7d10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ab01e4ca-9aa6-49a8-b083-79db7e933dab" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_e7c76fac-a7a0-458b-88ba-00bb64ca7d10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_8309f7ef-c47a-4eae-b0c5-786508736646" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_ab01e4ca-9aa6-49a8-b083-79db7e933dab" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_8309f7ef-c47a-4eae-b0c5-786508736646" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_5dcb7530-36bf-4574-b68d-b7359ac70ee0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_25173aa9-cfb4-4167-bab4-70b6a6b52e93" xlink:to="loc_us-gaap_DebtInstrumentAxis_5dcb7530-36bf-4574-b68d-b7359ac70ee0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5dcb7530-36bf-4574-b68d-b7359ac70ee0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_5dcb7530-36bf-4574-b68d-b7359ac70ee0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5dcb7530-36bf-4574-b68d-b7359ac70ee0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_a82e8222-ae08-4bd8-bf29-4b55410fbaab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_5dcb7530-36bf-4574-b68d-b7359ac70ee0" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_a82e8222-ae08-4bd8-bf29-4b55410fbaab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorDebentures69PercentDue2028Member_51ad684a-9f8d-4839-b7a4-02c432973b20" xlink:href="cinf-20250930.xsd#cinf_SeniorDebentures69PercentDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_a82e8222-ae08-4bd8-bf29-4b55410fbaab" xlink:to="loc_cinf_SeniorDebentures69PercentDue2028Member_51ad684a-9f8d-4839-b7a4-02c432973b20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorDebentures692PercentDue2028Member_b7429900-d55b-4245-bb1b-2cbacd1cb4c8" xlink:href="cinf-20250930.xsd#cinf_SeniorDebentures692PercentDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_a82e8222-ae08-4bd8-bf29-4b55410fbaab" xlink:to="loc_cinf_SeniorDebentures692PercentDue2028Member_b7429900-d55b-4245-bb1b-2cbacd1cb4c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeniorNotes6125PercentDue2034Member_30106ac7-584f-4871-a29f-3e916d26a3dc" xlink:href="cinf-20250930.xsd#cinf_SeniorNotes6125PercentDue2034Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_a82e8222-ae08-4bd8-bf29-4b55410fbaab" xlink:to="loc_cinf_SeniorNotes6125PercentDue2034Member_30106ac7-584f-4871-a29f-3e916d26a3dc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_b7f9ddbb-5258-43b9-acf2-e95d2bbc4af9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_b7f9ddbb-5258-43b9-acf2-e95d2bbc4af9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NotesPayableFairValueDisclosure_5c756415-c82b-4972-a752-6b02b210df86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NotesPayableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:to="loc_us-gaap_NotesPayableFairValueDisclosure_5c756415-c82b-4972-a752-6b02b210df86" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtFairValue_f1142aa2-981f-4608-bcfb-edcf4a8c2dfe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:to="loc_us-gaap_LongTermDebtFairValue_f1142aa2-981f-4608-bcfb-edcf4a8c2dfe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_1ff5b4ff-7c6c-4f1c-88a2-dae39b55155d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_1cfc8e5b-5a95-43fa-a782-973a29f106e9" xlink:to="loc_us-gaap_DebtInstrumentFairValue_1ff5b4ff-7c6c-4f1c-88a2-dae39b55155d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/FairValueMeasurementsFairValueofLifePolicyLoansDeferredAnnuitiesandStructuredSettlementsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#FairValueMeasurementsFairValueofLifePolicyLoansDeferredAnnuitiesandStructuredSettlementsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/FairValueMeasurementsFairValueofLifePolicyLoansDeferredAnnuitiesandStructuredSettlementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c1897763-c94d-4422-81b2-9c3e47e423c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_38cb7a3c-6d3d-46af-88a0-0d6dad51acbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c1897763-c94d-4422-81b2-9c3e47e423c7" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_38cb7a3c-6d3d-46af-88a0-0d6dad51acbc" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_38cb7a3c-6d3d-46af-88a0-0d6dad51acbc" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_f29b5ae4-4cfb-4d61-8b08-4286ffd830df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_a05174dc-cfac-44c4-a9bd-ed03ed6c9ad4" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_f29b5ae4-4cfb-4d61-8b08-4286ffd830df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_DeferredAnnuitiesMember_8b6133dd-3184-413a-81f2-fad9247f13d9" xlink:href="cinf-20250930.xsd#cinf_DeferredAnnuitiesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f29b5ae4-4cfb-4d61-8b08-4286ffd830df" xlink:to="loc_cinf_DeferredAnnuitiesMember_8b6133dd-3184-413a-81f2-fad9247f13d9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StructuredFinanceMember_34a520dd-2d76-48cf-a7bf-e99d87a05c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StructuredFinanceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_f29b5ae4-4cfb-4d61-8b08-4286ffd830df" xlink:to="loc_us-gaap_StructuredFinanceMember_34a520dd-2d76-48cf-a7bf-e99d87a05c4a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_35f5403c-4579-4710-b0bf-1baee73861e3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_38cb7a3c-6d3d-46af-88a0-0d6dad51acbc" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_35f5403c-4579-4710-b0bf-1baee73861e3" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_35f5403c-4579-4710-b0bf-1baee73861e3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_35f5403c-4579-4710-b0bf-1baee73861e3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_35f5403c-4579-4710-b0bf-1baee73861e3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e8a868ba-37d1-4562-84cf-20bed8da6978" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_35f5403c-4579-4710-b0bf-1baee73861e3" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e8a868ba-37d1-4562-84cf-20bed8da6978" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_f6030992-9f68-4d40-832e-6cd91a49d456" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e8a868ba-37d1-4562-84cf-20bed8da6978" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_f6030992-9f68-4d40-832e-6cd91a49d456" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_d646d701-6436-4c6d-a0b4-1450a52f5a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e8a868ba-37d1-4562-84cf-20bed8da6978" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_d646d701-6436-4c6d-a0b4-1450a52f5a7e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_b0fc1939-0c01-49a1-8bdf-80dac30be5b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_e8a868ba-37d1-4562-84cf-20bed8da6978" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_b0fc1939-0c01-49a1-8bdf-80dac30be5b9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LoansReceivableFairValueDisclosure_0e17d258-ca06-47c9-bfc6-d1c08827a8f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LoansReceivableFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c1897763-c94d-4422-81b2-9c3e47e423c7" xlink:to="loc_us-gaap_LoansReceivableFairValueDisclosure_0e17d258-ca06-47c9-bfc6-d1c08827a8f5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesRelatedToInvestmentContractsFairValueDisclosure_7c173b98-d3b0-45d9-a803-23b12013122b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesRelatedToInvestmentContractsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_c1897763-c94d-4422-81b2-9c3e47e423c7" xlink:to="loc_us-gaap_LiabilitiesRelatedToInvestmentContractsFairValueDisclosure_7c173b98-d3b0-45d9-a803-23b12013122b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/PropertyCasualtyLossandLossExpensesConsolidatedPropertyCasualtyLossandLossExpenseReservesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#PropertyCasualtyLossandLossExpensesConsolidatedPropertyCasualtyLossandLossExpenseReservesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/PropertyCasualtyLossandLossExpensesConsolidatedPropertyCasualtyLossandLossExpenseReservesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_a77dfe1c-8420-4143-91e9-3a81767ad1a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_a77dfe1c-8420-4143-91e9-3a81767ad1a4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseTable_a77dfe1c-8420-4143-91e9-3a81767ad1a4" xlink:to="loc_srt_ProductOrServiceAxis_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5" xlink:to="loc_srt_ProductsAndServicesDomain_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_26de8d14-332f-44f0-a6fc-623592f1bd06" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_d3d340d5-cd41-46e3-835e-67ed8e2ce8e5" xlink:to="loc_srt_ProductsAndServicesDomain_26de8d14-332f-44f0-a6fc-623592f1bd06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember_d790bf90-d83e-4674-a413-a75777cc4e69" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_26de8d14-332f-44f0-a6fc-623592f1bd06" xlink:to="loc_us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember_d790bf90-d83e-4674-a413-a75777cc4e69" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_b758188f-6098-4d15-93bd-60acad85756d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_b758188f-6098-4d15-93bd-60acad85756d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments_e5474cb3-e1f7-479b-bc92-b1a844748d3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments_e5474cb3-e1f7-479b-bc92-b1a844748d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_ff06cf4a-add9-4851-baf9-1594e6106fcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_ff06cf4a-add9-4851-baf9-1594e6106fcb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_cd569d1d-15fc-4b1c-9c59-768bb1536792" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense_cd569d1d-15fc-4b1c-9c59-768bb1536792" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_d104fb03-2a06-426c-beec-f4dfb28fee9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_d104fb03-2a06-426c-beec-f4dfb28fee9c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_3d5b4517-ffd0-4498-b957-d9ed5a52733b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1_3d5b4517-ffd0-4498-b957-d9ed5a52733b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_500f242e-8d4a-4d8c-ad15-fcf9c1c90ca4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1_500f242e-8d4a-4d8c-ad15-fcf9c1c90ca4" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_7861952e-9390-49f9-be1b-3501c7347f9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1_7861952e-9390-49f9-be1b-3501c7347f9a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_2faabd79-4401-422a-b63a-fe6d4f5e3f1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForLossesAndLossAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpenseLineItems_6de36318-16be-40c8-9bce-bfd698a23fe9" xlink:to="loc_us-gaap_PaymentsForLossesAndLossAdjustmentExpense_2faabd79-4401-422a-b63a-fe6d4f5e3f1c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet_8acf4ac3-5bd5-4f88-b950-d59c4dc49d4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments_a52ed00e-6c47-4b31-a892-04aaf06804c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceRecoverableForUnpaidClaimsAndClaimsAdjustments"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_7340735b-d93b-4156-8d9a-24b9788a64f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/PropertyCasualtyLossandLossExpensesNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#PropertyCasualtyLossandLossExpensesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/PropertyCasualtyLossandLossExpensesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems_d01be7c7-36e1-4c28-8664-764acc8f7d97" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersTable_f5acad05-7ca6-422a-a2b2-f6813c97498a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems_d01be7c7-36e1-4c28-8664-764acc8f7d97" xlink:to="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersTable_f5acad05-7ca6-422a-a2b2-f6813c97498a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_6f05b596-b85b-4e10-9549-d18a0b8629fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersTable_f5acad05-7ca6-422a-a2b2-f6813c97498a" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_6f05b596-b85b-4e10-9549-d18a0b8629fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_6f05b596-b85b-4e10-9549-d18a0b8629fd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_6f05b596-b85b-4e10-9549-d18a0b8629fd" xlink:to="loc_us-gaap_SegmentDomain_6f05b596-b85b-4e10-9549-d18a0b8629fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_6f05b596-b85b-4e10-9549-d18a0b8629fd" xlink:to="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_87d4a017-fbd7-4295-9074-59ce15469420" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:to="loc_cinf_LifeInsuranceMember_87d4a017-fbd7-4295-9074-59ce15469420" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_CommercialLinesInsuranceMember_5057b1d9-3778-43a0-8dde-e297ff4b714e" xlink:href="cinf-20250930.xsd#cinf_CommercialLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:to="loc_cinf_CommercialLinesInsuranceMember_5057b1d9-3778-43a0-8dde-e297ff4b714e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_PersonalLinesInsuranceMember_e2777728-76b4-4fb8-9f99-f32c78a284b7" xlink:href="cinf-20250930.xsd#cinf_PersonalLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:to="loc_cinf_PersonalLinesInsuranceMember_e2777728-76b4-4fb8-9f99-f32c78a284b7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ExcessandSurplusLinesInsuranceMember_befd0971-b0ce-411c-8df5-4e5b4b48e66b" xlink:href="cinf-20250930.xsd#cinf_ExcessandSurplusLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00391c36-f180-48c0-b7c6-7f5f99a932d6" xlink:to="loc_cinf_ExcessandSurplusLinesInsuranceMember_befd0971-b0ce-411c-8df5-4e5b4b48e66b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_8592f093-6d2d-4efb-8b26-febb18194ada" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersTable_f5acad05-7ca6-422a-a2b2-f6813c97498a" xlink:to="loc_srt_ProductOrServiceAxis_8592f093-6d2d-4efb-8b26-febb18194ada" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_8592f093-6d2d-4efb-8b26-febb18194ada_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_8592f093-6d2d-4efb-8b26-febb18194ada" xlink:to="loc_srt_ProductsAndServicesDomain_8592f093-6d2d-4efb-8b26-febb18194ada_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_8592f093-6d2d-4efb-8b26-febb18194ada" xlink:to="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_CommercialPropertySegmentMember_17646aaf-3ace-4d36-8a31-65aca0a66170" xlink:href="cinf-20250930.xsd#cinf_CommercialPropertySegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:to="loc_cinf_CommercialPropertySegmentMember_17646aaf-3ace-4d36-8a31-65aca0a66170" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_HomeownerMember_faaacfee-0eef-46f0-83d8-af38cba53051" xlink:href="cinf-20250930.xsd#cinf_HomeownerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:to="loc_cinf_HomeownerMember_faaacfee-0eef-46f0-83d8-af38cba53051" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_WorkersCompensationMember_1e86b531-cc04-479e-9dd5-92e648a48227" xlink:href="cinf-20250930.xsd#cinf_WorkersCompensationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:to="loc_cinf_WorkersCompensationMember_1e86b531-cc04-479e-9dd5-92e648a48227" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_CommercialCasualtySegmentMember_9553b8a8-515d-4beb-9c8d-1dc20f3dd9fd" xlink:href="cinf-20250930.xsd#cinf_CommercialCasualtySegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:to="loc_cinf_CommercialCasualtySegmentMember_9553b8a8-515d-4beb-9c8d-1dc20f3dd9fd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_CommercialAutoSegmentMember_88201d32-62dc-49fa-bb30-4a89d47738a9" xlink:href="cinf-20250930.xsd#cinf_CommercialAutoSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_624f9dff-b0ec-4355-afbc-56828081ec47" xlink:to="loc_cinf_CommercialAutoSegmentMember_88201d32-62dc-49fa-bb30-4a89d47738a9" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_ec59b2f6-789c-49a4-8146-d6a6d6058b50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems_d01be7c7-36e1-4c28-8664-764acc8f7d97" xlink:to="loc_us-gaap_LiabilityForClaimsAndClaimsAdjustmentExpense_ec59b2f6-789c-49a4-8146-d6a6d6058b50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_75ca99d2-4327-4e70-b67b-9ab46b22608b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersLineItems_d01be7c7-36e1-4c28-8664-764acc8f7d97" xlink:to="loc_us-gaap_SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense_75ca99d2-4327-4e70-b67b-9ab46b22608b" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/ReservesinAdditiontoAccountBalanceBasedonExpectedNoLapseGuaranteeBenefitsandExpectedPolicyAssessmentsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#ReservesinAdditiontoAccountBalanceBasedonExpectedNoLapseGuaranteeBenefitsandExpectedPolicyAssessmentsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/ReservesinAdditiontoAccountBalanceBasedonExpectedNoLapseGuaranteeBenefitsandExpectedPolicyAssessmentsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_5920d2bd-664e-4af5-819d-60b03b89c84b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable_f5d757f9-992e-49d8-8f94-a57430edea8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_5920d2bd-664e-4af5-819d-60b03b89c84b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable_f5d757f9-992e-49d8-8f94-a57430edea8a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_ea4d796c-cdef-4d43-9901-5d0aa80038ee" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable_f5d757f9-992e-49d8-8f94-a57430edea8a" xlink:to="loc_srt_ProductOrServiceAxis_ea4d796c-cdef-4d43-9901-5d0aa80038ee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ea4d796c-cdef-4d43-9901-5d0aa80038ee_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_ea4d796c-cdef-4d43-9901-5d0aa80038ee" xlink:to="loc_srt_ProductsAndServicesDomain_ea4d796c-cdef-4d43-9901-5d0aa80038ee_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_ea4d796c-cdef-4d43-9901-5d0aa80038ee" xlink:to="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_0ac10716-cacf-4b8b-a505-7d61929422c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_TermLifeInsuranceMember_0ac10716-cacf-4b8b-a505-7d61929422c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_b250861e-619e-4683-b15e-7a98829dad82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_b250861e-619e-4683-b15e-7a98829dad82" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLongdurationInsuranceProductLineMember_5f0c7ef1-04e7-46bd-81bd-2cb0597b343f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLongdurationInsuranceProductLineMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_OtherLongdurationInsuranceProductLineMember_5f0c7ef1-04e7-46bd-81bd-2cb0597b343f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFixedAnnuityMember_ed2aa3de-d9b8-4a3f-b37b-a3b6f630ec66" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_DeferredFixedAnnuityMember_ed2aa3de-d9b8-4a3f-b37b-a3b6f630ec66" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_2b1ace4a-d84c-4a94-8ce5-dbe8408d06f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_UniversalLifeMember_2b1ace4a-d84c-4a94-8ce5-dbe8408d06f4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StructuredSettlementAnnuityMember_67288aad-af0c-47da-808a-d3b3c5173968" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StructuredSettlementAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d8de845a-6ca9-4a06-a122-34a54151288b" xlink:to="loc_us-gaap_StructuredSettlementAnnuityMember_67288aad-af0c-47da-808a-d3b3c5173968" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_fdecbf27-61db-4424-a579-534216ec9255" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentTable_f5d757f9-992e-49d8-8f94-a57430edea8a" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_fdecbf27-61db-4424-a579-534216ec9255" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_fdecbf27-61db-4424-a579-534216ec9255_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_fdecbf27-61db-4424-a579-534216ec9255" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_fdecbf27-61db-4424-a579-534216ec9255_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_6d6f317a-71ad-4da6-bd15-90330ffef1ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_fdecbf27-61db-4424-a579-534216ec9255" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_6d6f317a-71ad-4da6-bd15-90330ffef1ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_0a5fa6fa-1d7d-454a-8dbd-6eef810bcc82" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_6d6f317a-71ad-4da6-bd15-90330ffef1ba" xlink:to="loc_cinf_LifePolicyReservesMember_0a5fa6fa-1d7d-454a-8dbd-6eef810bcc82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentcontractreservesMember_e3f13abd-5e8a-4d34-ac1a-1d07f2fa7456" xlink:href="cinf-20250930.xsd#cinf_InvestmentcontractreservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_6d6f317a-71ad-4da6-bd15-90330ffef1ba" xlink:to="loc_cinf_InvestmentcontractreservesMember_e3f13abd-5e8a-4d34-ac1a-1d07f2fa7456" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefits_1a73f416-cb3c-4e4d-be38-e29f4ca4db4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_5920d2bd-664e-4af5-819d-60b03b89c84b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefits_1a73f416-cb3c-4e4d-be38-e29f4ca4db4f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/LiabilityforFuturePolicyBenefitDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#LiabilityforFuturePolicyBenefitDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/LiabilityforFuturePolicyBenefitDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c3765371-e689-45ac-af40-b4a8ab268655" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c3765371-e689-45ac-af40-b4a8ab268655" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_cfdd6afa-de2c-4d79-a745-cf84b28bcffc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c3765371-e689-45ac-af40-b4a8ab268655" xlink:to="loc_srt_ProductOrServiceAxis_cfdd6afa-de2c-4d79-a745-cf84b28bcffc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_cfdd6afa-de2c-4d79-a745-cf84b28bcffc_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_cfdd6afa-de2c-4d79-a745-cf84b28bcffc" xlink:to="loc_srt_ProductsAndServicesDomain_cfdd6afa-de2c-4d79-a745-cf84b28bcffc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_480718b0-572a-4822-93df-f9270d6c11ca" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_cfdd6afa-de2c-4d79-a745-cf84b28bcffc" xlink:to="loc_srt_ProductsAndServicesDomain_480718b0-572a-4822-93df-f9270d6c11ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_810f2bf0-472e-491e-b158-d550196141db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_480718b0-572a-4822-93df-f9270d6c11ca" xlink:to="loc_us-gaap_TermLifeInsuranceMember_810f2bf0-472e-491e-b158-d550196141db" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_f1a9c654-080a-483a-969a-a7dd23c739c1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_480718b0-572a-4822-93df-f9270d6c11ca" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_f1a9c654-080a-483a-969a-a7dd23c739c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_0f0c30f6-dc15-4819-be1e-376689f2a6cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c3765371-e689-45ac-af40-b4a8ab268655" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_0f0c30f6-dc15-4819-be1e-376689f2a6cb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_0f0c30f6-dc15-4819-be1e-376689f2a6cb_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_0f0c30f6-dc15-4819-be1e-376689f2a6cb" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_0f0c30f6-dc15-4819-be1e-376689f2a6cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_3e907556-7486-425a-8c90-6b834379e043" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_0f0c30f6-dc15-4819-be1e-376689f2a6cb" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_3e907556-7486-425a-8c90-6b834379e043" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_ee310359-3537-48f7-bbac-32ee4fa9a9b4" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_3e907556-7486-425a-8c90-6b834379e043" xlink:to="loc_cinf_LifePolicyReservesMember_ee310359-3537-48f7-bbac-32ee4fa9a9b4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange_1593081d-07c4-44d2-a004-e241ce9359b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange_1593081d-07c4-44d2-a004-e241ce9359b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance_b5316420-d63e-47a8-810d-ab3865651340" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeCashFlowAndReinsurance_b5316420-d63e-47a8-810d-ab3865651340" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange_139247a5-bc85-41d6-a133-602e3556ef7c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseFromCashFlowChange_139247a5-bc85-41d6-a133-602e3556ef7c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_5e2b4b59-9c56-4e84-8fc9-c31b71f6d932" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_5e2b4b59-9c56-4e84-8fc9-c31b71f6d932" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_c6e1e617-fed8-42ca-9c89-f5b6f04da7cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_c6e1e617-fed8-42ca-9c89-f5b6f04da7cc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance_b7289d03-eeb5-4432-9ce0-99351c7feca1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumIssuance_b7289d03-eeb5-4432-9ce0-99351c7feca1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome_c362f310-13eb-4ecb-a440-539e5c7fdabc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumInterestIncome_c362f310-13eb-4ecb-a440-539e5c7fdabc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected_4d235100-39e9-48fa-809e-133ecde05ed8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumNetPremiumCollected_4d235100-39e9-48fa-809e-133ecde05ed8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_b9c2d644-e5fd-4288-9ce2-26e41259b6e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax_1100820a-a44b-4ea9-b6f3-3a7348c51d42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumRollForward_969c2f67-de2c-4682-9a39-f71a58e54861" xlink:to="loc_us-gaap_AociLiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeTax_1100820a-a44b-4ea9-b6f3-3a7348c51d42" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange_9eed4ecb-66a5-46a4-8a09-8a7f7d1c23ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedNetPremiumBeforeReinsuranceAfterDiscountRateChange"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange_c1ecd4f8-140c-4e34-971e-e612ff9209bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange_c1ecd4f8-140c-4e34-971e-e612ff9209bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance_72b39ccb-e9bf-4e43-a1cb-326d9d6dc1f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitOriginalDiscountRateBeforeCashFlowAndReinsurance_72b39ccb-e9bf-4e43-a1cb-326d9d6dc1f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange_25a8153f-de00-4d3a-bf47-434d0f3adaf7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseFromCashFlowChange_25a8153f-de00-4d3a-bf47-434d0f3adaf7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_40afa414-5e18-4924-a170-0c85660e02ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_40afa414-5e18-4924-a170-0c85660e02ca" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_a824438f-165f-445b-8770-e00860bd436a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_a824438f-165f-445b-8770-e00860bd436a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance_5bdabdf5-2dd7-4a82-a9b0-b505953fe8f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitIssuance_5bdabdf5-2dd7-4a82-a9b0-b505953fe8f7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense_84252b6d-4149-40c3-ba4a-25e670ed17f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitInterestExpense_84252b6d-4149-40c3-ba4a-25e670ed17f3" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits_7460c151-0849-4e26-9695-2d4e121cd5ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitsPaymentForBenefits_7460c151-0849-4e26-9695-2d4e121cd5ed" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_4bd9897a-fb03-494d-b2e9-5370299d8f70" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureBenefitOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax_9308494b-d688-4579-acbc-9478cb58f22d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitRollForward_52f388b5-cc74-4b31-9307-860048860040" xlink:to="loc_us-gaap_AociLiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeTax_9308494b-d688-4579-acbc-9478cb58f22d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange_559980f1-8cfb-4c85-b670-dfeef41965a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:href="cinf-20250930.xsd#cinf_NetLiabilityForFuturePolicyBenefitsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:to="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LiabilityForFuturePolicyBenefitBeforeImpactOfFlooringAtCohortLevelBeforeReinsurance_f3ecae70-7b93-415e-9762-7c566cb62a67" xlink:href="cinf-20250930.xsd#cinf_LiabilityForFuturePolicyBenefitBeforeImpactOfFlooringAtCohortLevelBeforeReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_cinf_LiabilityForFuturePolicyBenefitBeforeImpactOfFlooringAtCohortLevelBeforeReinsurance_f3ecae70-7b93-415e-9762-7c566cb62a67" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LiabilityForFuturePolicyBenefitImpactOfFlooringAtCohortLevel_0ca00aec-7de6-4a53-895b-869132ac8dbf" xlink:href="cinf-20250930.xsd#cinf_LiabilityForFuturePolicyBenefitImpactOfFlooringAtCohortLevel"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_cinf_LiabilityForFuturePolicyBenefitImpactOfFlooringAtCohortLevel_0ca00aec-7de6-4a53-895b-869132ac8dbf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefits_31e9423f-00f8-4dba-8b7d-17f27543959f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefits"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefits_31e9423f-00f8-4dba-8b7d-17f27543959f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitReinsuranceRecoverableAfterAllowance_271a4ba2-6163-4a04-9561-5607e2c47451" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitReinsuranceRecoverableAfterAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitReinsuranceRecoverableAfterAllowance_271a4ba2-6163-4a04-9561-5607e2c47451" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_EffectOfDiscountRateAssumptionChangesOnReinsuranceRecoverable_830bad2d-e80d-46c9-9efd-f0f6cd2f1fe8" xlink:href="cinf-20250930.xsd#cinf_EffectOfDiscountRateAssumptionChangesOnReinsuranceRecoverable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_cinf_EffectOfDiscountRateAssumptionChangesOnReinsuranceRecoverable_830bad2d-e80d-46c9-9efd-f0f6cd2f1fe8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance_19a03c45-4542-44f5-aecc-5622ca73d34f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_NetLiabilityForFuturePolicyBenefitsRollForward_fbb886c5-7bc4-4586-8432-f4ba38728c45" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsurance_19a03c45-4542-44f5-aecc-5622ca73d34f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration_fe64ce95-3e96-4503-9822-1cf53b21f0d8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitByProductSegmentLineItems_e762f4b5-8915-462c-a78b-82af1c5be28b" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageDuration_fe64ce95-3e96-4503-9822-1cf53b21f0d8" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/LifePolicyandInvestmentContractReservesNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#LifePolicyandInvestmentContractReservesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/LifePolicyandInvestmentContractReservesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_041bf13b-2695-499f-b264-674c5a895721" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_2e55c98c-8a36-4945-8964-69bfb45590ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_041bf13b-2695-499f-b264-674c5a895721" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_2e55c98c-8a36-4945-8964-69bfb45590ed" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_6bf7b08c-f6bf-49d6-9f78-e85958d67025" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_2e55c98c-8a36-4945-8964-69bfb45590ed" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_6bf7b08c-f6bf-49d6-9f78-e85958d67025" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_6bf7b08c-f6bf-49d6-9f78-e85958d67025_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_6bf7b08c-f6bf-49d6-9f78-e85958d67025" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_6bf7b08c-f6bf-49d6-9f78-e85958d67025_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_050964ac-60c2-4a3f-9f6b-205ae91ed0a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_6bf7b08c-f6bf-49d6-9f78-e85958d67025" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_050964ac-60c2-4a3f-9f6b-205ae91ed0a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_8dfcc6b3-b84a-409c-b700-96dbe738b223" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_050964ac-60c2-4a3f-9f6b-205ae91ed0a7" xlink:to="loc_cinf_LifePolicyReservesMember_8dfcc6b3-b84a-409c-b700-96dbe738b223" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_4c20a8e2-979f-4cec-b726-58a4986531a8" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_050964ac-60c2-4a3f-9f6b-205ae91ed0a7" xlink:to="loc_cinf_LifeInsuranceMember_4c20a8e2-979f-4cec-b726-58a4986531a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_a021ecf9-a463-4e1b-b8d9-9da13168d264" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_2e55c98c-8a36-4945-8964-69bfb45590ed" xlink:to="loc_srt_ProductOrServiceAxis_a021ecf9-a463-4e1b-b8d9-9da13168d264" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a021ecf9-a463-4e1b-b8d9-9da13168d264_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_a021ecf9-a463-4e1b-b8d9-9da13168d264" xlink:to="loc_srt_ProductsAndServicesDomain_a021ecf9-a463-4e1b-b8d9-9da13168d264_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e7d07564-6d87-4fc8-ba21-d9f9dc38c43c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_a021ecf9-a463-4e1b-b8d9-9da13168d264" xlink:to="loc_srt_ProductsAndServicesDomain_e7d07564-6d87-4fc8-ba21-d9f9dc38c43c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_39aff011-9feb-4668-a6b8-bafe3dce820f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e7d07564-6d87-4fc8-ba21-d9f9dc38c43c" xlink:to="loc_us-gaap_TermLifeInsuranceMember_39aff011-9feb-4668-a6b8-bafe3dce820f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_29eaa5ff-9ed0-4079-855e-e3df467cdc2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e7d07564-6d87-4fc8-ba21-d9f9dc38c43c" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_29eaa5ff-9ed0-4079-855e-e3df467cdc2f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract_1b9e6016-5963-4571-ab2e-93f900b41173" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_041bf13b-2695-499f-b264-674c5a895721" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract_1b9e6016-5963-4571-ab2e-93f900b41173" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_DiscountRateAssumptionChangesIncludedInImpactOfFlooringAtCohortLevel_45ac1786-f66b-49a1-ad8e-566cb6523560" xlink:href="cinf-20250930.xsd#cinf_DiscountRateAssumptionChangesIncludedInImpactOfFlooringAtCohortLevel"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract_1b9e6016-5963-4571-ab2e-93f900b41173" xlink:to="loc_cinf_DiscountRateAssumptionChangesIncludedInImpactOfFlooringAtCohortLevel_45ac1786-f66b-49a1-ad8e-566cb6523560" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitAdverseDevelopmentExpense_698f789b-fde1-4efe-8db9-12385259d19d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitAdverseDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitAfterReinsuranceAbstract_1b9e6016-5963-4571-ab2e-93f900b41173" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitAdverseDevelopmentExpense_698f789b-fde1-4efe-8db9-12385259d19d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/UndiscountedandDiscountedFutureBenefitPaymentsandGrossPremiumsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#UndiscountedandDiscountedFutureBenefitPaymentsandGrossPremiumsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/UndiscountedandDiscountedFutureBenefitPaymentsandGrossPremiumsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_efa74cdb-5e08-4b3a-b586-d6ad751f5e44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_efa74cdb-5e08-4b3a-b586-d6ad751f5e44" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_acafb840-8ba1-478d-9148-bf6dfa924c9c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_efa74cdb-5e08-4b3a-b586-d6ad751f5e44" xlink:to="loc_srt_ProductOrServiceAxis_acafb840-8ba1-478d-9148-bf6dfa924c9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_acafb840-8ba1-478d-9148-bf6dfa924c9c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_acafb840-8ba1-478d-9148-bf6dfa924c9c" xlink:to="loc_srt_ProductsAndServicesDomain_acafb840-8ba1-478d-9148-bf6dfa924c9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_4e69c21d-5b2d-45bd-a861-22d4d53b090e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_acafb840-8ba1-478d-9148-bf6dfa924c9c" xlink:to="loc_srt_ProductsAndServicesDomain_4e69c21d-5b2d-45bd-a861-22d4d53b090e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_03b3285e-f756-43cd-903e-31b0485fe26b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_4e69c21d-5b2d-45bd-a861-22d4d53b090e" xlink:to="loc_us-gaap_TermLifeInsuranceMember_03b3285e-f756-43cd-903e-31b0485fe26b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_9c8b7f53-3096-4f86-8e87-b2e73045350c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_4e69c21d-5b2d-45bd-a861-22d4d53b090e" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_9c8b7f53-3096-4f86-8e87-b2e73045350c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_03cfd086-49b8-448a-813c-22f92321ec59" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_efa74cdb-5e08-4b3a-b586-d6ad751f5e44" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_03cfd086-49b8-448a-813c-22f92321ec59" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_03cfd086-49b8-448a-813c-22f92321ec59_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_03cfd086-49b8-448a-813c-22f92321ec59" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_03cfd086-49b8-448a-813c-22f92321ec59_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_c80eb210-5d5f-4d2c-9552-e1f655593df6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_03cfd086-49b8-448a-813c-22f92321ec59" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_c80eb210-5d5f-4d2c-9552-e1f655593df6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_ef37254d-498c-4e3f-b780-9179167d5a73" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_c80eb210-5d5f-4d2c-9552-e1f655593df6" xlink:to="loc_cinf_LifePolicyReservesMember_ef37254d-498c-4e3f-b780-9179167d5a73" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance_0ecf83bc-d47c-4b45-8514-fb98e119767f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitUndiscountedBeforeReinsurance_0ecf83bc-d47c-4b45-8514-fb98e119767f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance_02f33c57-2ecf-4ad2-9d9e-ca93ffaaafd8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumUndiscountedBeforeReinsurance_02f33c57-2ecf-4ad2-9d9e-ca93ffaaafd8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange_6e666698-83f2-43dc-8965-1f7c5ab94c4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFuturePolicyBenefitBeforeReinsuranceAfterDiscountRateChange_6e666698-83f2-43dc-8965-1f7c5ab94c4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance_7edfb466-42f9-4d2d-87b5-4b3c68df25b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_b312a072-1ca9-491f-b4ad-26f81820ebe5" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitExpectedFutureGrossPremiumDiscountedBeforeReinsurance_7edfb466-42f9-4d2d-87b5-4b3c68df25b6" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/RevenueandInterestRecognizedinIncomeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#RevenueandInterestRecognizedinIncomeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/RevenueandInterestRecognizedinIncomeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_6f5b7f83-6bba-406a-93ce-3cba03baaa68" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_d1d18586-8d19-4112-baf6-090d48697c98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_6f5b7f83-6bba-406a-93ce-3cba03baaa68" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_d1d18586-8d19-4112-baf6-090d48697c98" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_e9c94f09-3c12-4978-9c51-9984b145f737" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_d1d18586-8d19-4112-baf6-090d48697c98" xlink:to="loc_srt_ProductOrServiceAxis_e9c94f09-3c12-4978-9c51-9984b145f737" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e9c94f09-3c12-4978-9c51-9984b145f737_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_e9c94f09-3c12-4978-9c51-9984b145f737" xlink:to="loc_srt_ProductsAndServicesDomain_e9c94f09-3c12-4978-9c51-9984b145f737_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_00403a7e-4ab3-4b86-8287-fa4ea7af579a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_e9c94f09-3c12-4978-9c51-9984b145f737" xlink:to="loc_srt_ProductsAndServicesDomain_00403a7e-4ab3-4b86-8287-fa4ea7af579a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_59e767d7-995b-4e9f-b4cd-88ad049951e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_00403a7e-4ab3-4b86-8287-fa4ea7af579a" xlink:to="loc_us-gaap_TermLifeInsuranceMember_59e767d7-995b-4e9f-b4cd-88ad049951e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_da3fe19f-2980-4ac5-959f-f1459066d053" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_00403a7e-4ab3-4b86-8287-fa4ea7af579a" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_da3fe19f-2980-4ac5-959f-f1459066d053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_a478b2e9-28bc-455b-aff9-d9b3d6bdf704" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_d1d18586-8d19-4112-baf6-090d48697c98" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_a478b2e9-28bc-455b-aff9-d9b3d6bdf704" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_a478b2e9-28bc-455b-aff9-d9b3d6bdf704_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_a478b2e9-28bc-455b-aff9-d9b3d6bdf704" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_a478b2e9-28bc-455b-aff9-d9b3d6bdf704_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_e6402ef8-844b-44b1-aecb-c75d03e6298a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_a478b2e9-28bc-455b-aff9-d9b3d6bdf704" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_e6402ef8-844b-44b1-aecb-c75d03e6298a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_4a60ded8-a081-48f4-b761-b68d71483f2d" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_e6402ef8-844b-44b1-aecb-c75d03e6298a" xlink:to="loc_cinf_LifePolicyReservesMember_4a60ded8-a081-48f4-b761-b68d71483f2d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome_78f7be8b-d550-4086-90d4-639d6a16e2e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_6f5b7f83-6bba-406a-93ce-3cba03baaa68" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitGrossPremiumIncome_78f7be8b-d550-4086-90d4-639d6a16e2e6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitInterestExpense_fe54ff24-e011-4ff7-9b5b-767ad2b3ce5c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitInterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_6f5b7f83-6bba-406a-93ce-3cba03baaa68" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitInterestExpense_fe54ff24-e011-4ff7-9b5b-767ad2b3ce5c" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/WeightedAverageInterestRateforLifePolicyProductsDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#WeightedAverageInterestRateforLifePolicyProductsDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/WeightedAverageInterestRateforLifePolicyProductsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_1ae9f84b-23f9-417c-a047-bba885a750aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c033f0af-807c-4071-9a6e-5991c0d0f93c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_1ae9f84b-23f9-417c-a047-bba885a750aa" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c033f0af-807c-4071-9a6e-5991c0d0f93c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_8d3420ad-956c-41b7-a4fd-69596af9d54c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c033f0af-807c-4071-9a6e-5991c0d0f93c" xlink:to="loc_srt_ProductOrServiceAxis_8d3420ad-956c-41b7-a4fd-69596af9d54c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_8d3420ad-956c-41b7-a4fd-69596af9d54c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_8d3420ad-956c-41b7-a4fd-69596af9d54c" xlink:to="loc_srt_ProductsAndServicesDomain_8d3420ad-956c-41b7-a4fd-69596af9d54c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_ba64cc8f-6ff8-4400-9062-7b161aa0f4fb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_8d3420ad-956c-41b7-a4fd-69596af9d54c" xlink:to="loc_srt_ProductsAndServicesDomain_ba64cc8f-6ff8-4400-9062-7b161aa0f4fb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_1b85a521-14cc-46a4-bded-0e6eacdcc283" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ba64cc8f-6ff8-4400-9062-7b161aa0f4fb" xlink:to="loc_us-gaap_TermLifeInsuranceMember_1b85a521-14cc-46a4-bded-0e6eacdcc283" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_d2c6177c-8ead-4884-8d26-c552c4b4e882" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_ba64cc8f-6ff8-4400-9062-7b161aa0f4fb" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_d2c6177c-8ead-4884-8d26-c552c4b4e882" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_d7c098e0-f4d0-4d46-8c50-a647a80eddd7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityTable_c033f0af-807c-4071-9a6e-5991c0d0f93c" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_d7c098e0-f4d0-4d46-8c50-a647a80eddd7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_d7c098e0-f4d0-4d46-8c50-a647a80eddd7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_d7c098e0-f4d0-4d46-8c50-a647a80eddd7" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_d7c098e0-f4d0-4d46-8c50-a647a80eddd7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_ea8aeb70-a7c0-4076-ae4b-6fecc56b4da9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_d7c098e0-f4d0-4d46-8c50-a647a80eddd7" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_ea8aeb70-a7c0-4076-ae4b-6fecc56b4da9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifePolicyReservesMember_e57938de-1d7c-4689-bd87-ab4e9bcd7a6b" xlink:href="cinf-20250930.xsd#cinf_LifePolicyReservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_ea8aeb70-a7c0-4076-ae4b-6fecc56b4da9" xlink:to="loc_cinf_LifePolicyReservesMember_e57938de-1d7c-4689-bd87-ab4e9bcd7a6b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate_e8bd2354-5036-4757-a64a-d56175d3f9d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_1ae9f84b-23f9-417c-a047-bba885a750aa" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitWeightedAverageInterestAccretionRate_e8bd2354-5036-4757-a64a-d56175d3f9d4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate_1da082a0-7090-4361-a5e2-29b51a6a2ad6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LiabilityForFuturePolicyBenefitActivityLineItems_1ae9f84b-23f9-417c-a047-bba885a750aa" xlink:to="loc_us-gaap_LiabilityForFuturePolicyBenefitCurrentWeightedAverageDiscountRate_1da082a0-7090-4361-a5e2-29b51a6a2ad6" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/ChangesinPolicyholdersAccountBalancesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#ChangesinPolicyholdersAccountBalancesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/ChangesinPolicyholdersAccountBalancesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceTable_d47dac24-0b04-46b8-a48d-de78e86707db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:to="loc_us-gaap_PolicyholderAccountBalanceTable_d47dac24-0b04-46b8-a48d-de78e86707db" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_464578f1-fafc-4238-8870-518857e44f7d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceTable_d47dac24-0b04-46b8-a48d-de78e86707db" xlink:to="loc_srt_ProductOrServiceAxis_464578f1-fafc-4238-8870-518857e44f7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_464578f1-fafc-4238-8870-518857e44f7d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_464578f1-fafc-4238-8870-518857e44f7d" xlink:to="loc_srt_ProductsAndServicesDomain_464578f1-fafc-4238-8870-518857e44f7d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2171fe2d-ed9e-4eec-9fd7-f2d589e80002" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_464578f1-fafc-4238-8870-518857e44f7d" xlink:to="loc_srt_ProductsAndServicesDomain_2171fe2d-ed9e-4eec-9fd7-f2d589e80002" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFixedAnnuityMember_955c8c60-ac9f-4a7c-b550-9593326f0441" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2171fe2d-ed9e-4eec-9fd7-f2d589e80002" xlink:to="loc_us-gaap_DeferredFixedAnnuityMember_955c8c60-ac9f-4a7c-b550-9593326f0441" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_da49637d-021f-4cf3-8a8b-418e2ae173fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2171fe2d-ed9e-4eec-9fd7-f2d589e80002" xlink:to="loc_us-gaap_UniversalLifeMember_da49637d-021f-4cf3-8a8b-418e2ae173fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_36427609-cb6d-468b-bea3-6e93a26e947a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceTable_d47dac24-0b04-46b8-a48d-de78e86707db" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_36427609-cb6d-468b-bea3-6e93a26e947a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_36427609-cb6d-468b-bea3-6e93a26e947a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_36427609-cb6d-468b-bea3-6e93a26e947a" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_36427609-cb6d-468b-bea3-6e93a26e947a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_a5e3699e-2b13-4522-ac6a-7452f223d962" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_36427609-cb6d-468b-bea3-6e93a26e947a" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_a5e3699e-2b13-4522-ac6a-7452f223d962" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentcontractreservesMember_c70ba087-0c6b-4b53-94a8-973401824508" xlink:href="cinf-20250930.xsd#cinf_InvestmentcontractreservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_a5e3699e-2b13-4522-ac6a-7452f223d962" xlink:to="loc_cinf_InvestmentcontractreservesMember_c70ba087-0c6b-4b53-94a8-973401824508" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:to="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderFunds_1cd992ca-f76e-4989-a921-b1a70fafc958" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_PolicyholderFunds_1cd992ca-f76e-4989-a921-b1a70fafc958" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalancePremiumReceived_17f22a43-736e-49c0-b232-1a6b2777d33f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalancePremiumReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_PolicyholderAccountBalancePremiumReceived_17f22a43-736e-49c0-b232-1a6b2777d33f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalancePolicyCharge_809a00a4-f99a-47b5-aea5-874b9c7fcd7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalancePolicyCharge"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_PolicyholderAccountBalancePolicyCharge_809a00a4-f99a-47b5-aea5-874b9c7fcd7b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceSurrenderAndWithdrawal_22e62521-2d96-414d-a8d7-40884443b5a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceSurrenderAndWithdrawal"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_PolicyholderAccountBalanceSurrenderAndWithdrawal_22e62521-2d96-414d-a8d7-40884443b5a3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceBenefitPayment_540c0d4f-6860-4238-a5c8-5ec44a79a625" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceBenefitPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_PolicyholderAccountBalanceBenefitPayment_540c0d4f-6860-4238-a5c8-5ec44a79a625" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestCreditedToPolicyholdersAccountBalances_a16783dc-ebf5-419d-8225-e38b621325c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestCreditedToPolicyholdersAccountBalances"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceRollForward_14e9d4a2-193e-4f83-9ab4-b2939ec2a359" xlink:to="loc_us-gaap_InterestCreditedToPolicyholdersAccountBalances_a16783dc-ebf5-419d-8225-e38b621325c8" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderFunds_e45d4a7a-acf3-4d98-bac8-68a70bcd41b2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate_7b225723-c11a-45c3-8b21-aab339dcd670" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:to="loc_us-gaap_PolicyholderAccountBalanceWeightedAverageCreditingRate_7b225723-c11a-45c3-8b21-aab339dcd670" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceNetAmountAtRisk_2a22661c-eb7c-48de-9450-0cd58e506819" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceNetAmountAtRisk"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:to="loc_us-gaap_PolicyholderAccountBalanceNetAmountAtRisk_2a22661c-eb7c-48de-9450-0cd58e506819" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashSurrenderValueDuePolicyholdersAmount_205fee0e-e3ac-4f47-a80b-01ca7f05a742" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashSurrenderValueDuePolicyholdersAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceLineItems_76497ca8-7eb1-4002-9a82-f53f79c11faa" xlink:to="loc_us-gaap_CashSurrenderValueDuePolicyholdersAmount_205fee0e-e3ac-4f47-a80b-01ca7f05a742" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/AccountValuesbyRangeofGuaranteedMinimumCreditingRatesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#AccountValuesbyRangeofGuaranteedMinimumCreditingRatesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/AccountValuesbyRangeofGuaranteedMinimumCreditingRatesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems_715f9b88-3edd-4353-8428-3b21fa723a57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems_715f9b88-3edd-4353-8428-3b21fa723a57" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_a20f9f83-b4d5-4aab-a44b-2974314f536c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:to="loc_srt_ProductOrServiceAxis_a20f9f83-b4d5-4aab-a44b-2974314f536c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_a20f9f83-b4d5-4aab-a44b-2974314f536c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_a20f9f83-b4d5-4aab-a44b-2974314f536c" xlink:to="loc_srt_ProductsAndServicesDomain_a20f9f83-b4d5-4aab-a44b-2974314f536c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_2ae56179-8c64-4b46-9565-c4528a7ceaf5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_a20f9f83-b4d5-4aab-a44b-2974314f536c" xlink:to="loc_srt_ProductsAndServicesDomain_2ae56179-8c64-4b46-9565-c4528a7ceaf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFixedAnnuityMember_ba027e92-b737-4c31-8c7e-bcfe2587d2eb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2ae56179-8c64-4b46-9565-c4528a7ceaf5" xlink:to="loc_us-gaap_DeferredFixedAnnuityMember_ba027e92-b737-4c31-8c7e-bcfe2587d2eb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_97265188-5e38-48a7-9eed-4b5717184729" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_2ae56179-8c64-4b46-9565-c4528a7ceaf5" xlink:to="loc_us-gaap_UniversalLifeMember_97265188-5e38-48a7-9eed-4b5717184729" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesByIndustryAxis_664bc026-a1d7-4f80-a373-5f170582f596" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesByIndustryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:to="loc_us-gaap_EquitySecuritiesByIndustryAxis_664bc026-a1d7-4f80-a373-5f170582f596" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_664bc026-a1d7-4f80-a373-5f170582f596_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_664bc026-a1d7-4f80-a373-5f170582f596" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_664bc026-a1d7-4f80-a373-5f170582f596_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquitySecuritiesIndustryMember_2f1eae34-b6bf-452b-b169-118ccc910fff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquitySecuritiesIndustryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_EquitySecuritiesByIndustryAxis_664bc026-a1d7-4f80-a373-5f170582f596" xlink:to="loc_us-gaap_EquitySecuritiesIndustryMember_2f1eae34-b6bf-452b-b169-118ccc910fff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentcontractreservesMember_7f45be7e-96e9-4897-97f6-3bb02efe4f39" xlink:href="cinf-20250930.xsd#cinf_InvestmentcontractreservesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquitySecuritiesIndustryMember_2f1eae34-b6bf-452b-b169-118ccc910fff" xlink:to="loc_cinf_InvestmentcontractreservesMember_7f45be7e-96e9-4897-97f6-3bb02efe4f39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis_d648c95a-a1a7-4513-a805-6cb87bbd2408" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis_d648c95a-a1a7-4513-a805-6cb87bbd2408" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_d648c95a-a1a7-4513-a805-6cb87bbd2408_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis_d648c95a-a1a7-4513-a805-6cb87bbd2408" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_d648c95a-a1a7-4513-a805-6cb87bbd2408_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_cf90872e-13a0-4e4c-9e39-e802509e1376" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeAxis_d648c95a-a1a7-4513-a805-6cb87bbd2408" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_cf90872e-13a0-4e4c-9e39-e802509e1376" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0300To0399Member_1605e20f-28c2-4de8-87c2-99d0f5a3f9dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0300To0399Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_cf90872e-13a0-4e4c-9e39-e802509e1376" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0300To0399Member_1605e20f-28c2-4de8-87c2-99d0f5a3f9dc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0400AndGreaterMember_d3437c55-44ec-4187-bb7a-bcda3e83d743" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0400AndGreaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_cf90872e-13a0-4e4c-9e39-e802509e1376" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0400AndGreaterMember_d3437c55-44ec-4187-bb7a-bcda3e83d743" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0200To0299Member_dd91b7c1-92c9-4170-8460-cfca687224d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0200To0299Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeDomain_cf90872e-13a0-4e4c-9e39-e802509e1376" xlink:to="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateRangeFrom0200To0299Member_dd91b7c1-92c9-4170-8460-cfca687224d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis_27a02463-7363-4208-82a0-c0d32d1c8374" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateTable_30e7c806-58a9-4374-b84e-e5456984d67f" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis_27a02463-7363-4208-82a0-c0d32d1c8374" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_27a02463-7363-4208-82a0-c0d32d1c8374_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis_27a02463-7363-4208-82a0-c0d32d1c8374" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_27a02463-7363-4208-82a0-c0d32d1c8374_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateAxis_27a02463-7363-4208-82a0-c0d32d1c8374" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember_6c6dce8c-8901-49ae-b2f4-4b5e20fa8a0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAtGuaranteedMinimumCreditingRateMember_6c6dce8c-8901-49ae-b2f4-4b5e20fa8a0d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member_f1dd123b-42d3-4a17-9cfe-17046d49199e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0001To0050Member_f1dd123b-42d3-4a17-9cfe-17046d49199e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0150Member_7723dfa4-27f5-4389-bbba-fb304e3effe4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0150Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0051To0150Member_7723dfa4-27f5-4389-bbba-fb304e3effe4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0151AndGreaterMember_562cefb1-6938-4781-8898-0d7ba299f78a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0151AndGreaterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateDomain_e515f6fe-7379-43d3-9dd5-f375f2e3cb7b" xlink:to="loc_us-gaap_PolicyholderAccountBalanceAboveGuaranteedMinimumCreditingRateRangeFrom0151AndGreaterMember_562cefb1-6938-4781-8898-0d7ba299f78a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderFunds_a3d18ce1-2c2a-4794-a755-edb2a495e566" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderFunds"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PolicyholderAccountBalanceGuaranteedMinimumCreditingRateLineItems_715f9b88-3edd-4353-8428-3b21fa723a57" xlink:to="loc_us-gaap_PolicyholderFunds_a3d18ce1-2c2a-4794-a755-edb2a495e566" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/OtherAdditionalLiabilityRollforwardDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#OtherAdditionalLiabilityRollforwardDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/OtherAdditionalLiabilityRollforwardDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems_806044ba-76d0-4298-a081-fa947a0b5703" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceActivityTable_bdae48b9-f936-4b7c-a57c-e4f8e160ac93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceActivityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems_806044ba-76d0-4298-a081-fa947a0b5703" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceActivityTable_bdae48b9-f936-4b7c-a57c-e4f8e160ac93" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_f431cbca-c507-445a-9ff2-f958f8b4e3ae" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceActivityTable_bdae48b9-f936-4b7c-a57c-e4f8e160ac93" xlink:to="loc_srt_ProductOrServiceAxis_f431cbca-c507-445a-9ff2-f958f8b4e3ae" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f431cbca-c507-445a-9ff2-f958f8b4e3ae_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_f431cbca-c507-445a-9ff2-f958f8b4e3ae" xlink:to="loc_srt_ProductsAndServicesDomain_f431cbca-c507-445a-9ff2-f958f8b4e3ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_7ee36d30-c007-4730-9612-2460625a4ea9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_f431cbca-c507-445a-9ff2-f958f8b4e3ae" xlink:to="loc_srt_ProductsAndServicesDomain_7ee36d30-c007-4730-9612-2460625a4ea9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_6c62365b-ac67-46f8-b8b1-5e3ab8dbb86b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_7ee36d30-c007-4730-9612-2460625a4ea9" xlink:to="loc_us-gaap_UniversalLifeMember_6c62365b-ac67-46f8-b8b1-5e3ab8dbb86b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems_806044ba-76d0-4298-a081-fa947a0b5703" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChangeAfterShadowReserveAdjustment_5cf30f84-7aa1-4736-ab83-917a47fc14b6" xlink:href="cinf-20250930.xsd#cinf_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChangeAfterShadowReserveAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_cinf_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChangeAfterShadowReserveAdjustment_5cf30f84-7aa1-4736-ab83-917a47fc14b6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance_febfb26d-6e52-4317-8dea-ce4dc804be51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeCashFlowAndReinsurance_febfb26d-6e52-4317-8dea-ce4dc804be51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange_8ef332ee-8e3e-42e7-9ca3-4f6384f8ea50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseFromCashFlowChange_8ef332ee-8e3e-42e7-9ca3-4f6384f8ea50" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_dce2ffd7-037b-4152-84e7-e3f7b92e892a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceCumulativeIncreaseDecreaseOfActualVarianceFromExpectedExperience_dce2ffd7-037b-4152-84e7-e3f7b92e892a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_469e20ba-a67e-4928-829b-b82cf81e2ff2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceOriginalDiscountRateBeforeReinsuranceAfterCashFlowChange_469e20ba-a67e-4928-829b-b82cf81e2ff2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense_b822715d-9a8c-4cec-84f5-87388ef5adc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceInterestIncomeExpense_b822715d-9a8c-4cec-84f5-87388ef5adc7" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment_0137c104-2f8b-46c1-91ed-505353c0466c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceBenefitPayment_0137c104-2f8b-46c1-91ed-505353c0466c" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected_a8d1722c-e61c-4ac5-8d6c-ff8b8c7a33cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceNetPremiumCollected_a8d1722c-e61c-4ac5-8d6c-ff8b8c7a33cd" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceIncreaseDecreaseFromDiscountRateChange_16d62d50-9c34-4021-97d5-bc9540421dd4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceIncreaseDecreaseFromDiscountRateChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceIncreaseDecreaseFromDiscountRateChange_16d62d50-9c34-4021-97d5-bc9540421dd4" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChange_7e664f56-1c11-43f9-bce1-032ad66a2bb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChange_7e664f56-1c11-43f9-bce1-032ad66a2bb4" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AdditionalLiabilityLongDurationInsuranceShadowReserveAdjustments_3424272c-a119-4b01-b0b6-d84e30d42180" xlink:href="cinf-20250930.xsd#cinf_AdditionalLiabilityLongDurationInsuranceShadowReserveAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_cinf_AdditionalLiabilityLongDurationInsuranceShadowReserveAdjustments_3424272c-a119-4b01-b0b6-d84e30d42180" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChangeAfterShadowReserveAdjustment_3427f6bc-65d8-4f28-a6ab-828f55f98738" xlink:href="cinf-20250930.xsd#cinf_AdditionalLiabilityLongDurationInsuranceBeforeReinsuranceAfterDiscountRateChangeAfterShadowReserveAdjustment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceReinsuranceRecoverableAfterAllowance_4bd52724-01c0-407c-bfb4-4fd715e3032c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceReinsuranceRecoverableAfterAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceRollForward_9632d20d-5779-4d58-8ffa-26ae08bdb7dd" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceReinsuranceRecoverableAfterAllowance_4bd52724-01c0-407c-bfb4-4fd715e3032c" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance_f8bfe428-6552-41ae-a524-41c98342235f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems_806044ba-76d0-4298-a081-fa947a0b5703" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceAfterReinsurance_f8bfe428-6552-41ae-a524-41c98342235f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration_55eea54b-4cd8-4ebd-a90d-a959aa46b365" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceLineItems_806044ba-76d0-4298-a081-fa947a0b5703" xlink:to="loc_us-gaap_AdditionalLiabilityLongDurationInsuranceWeightedAverageDuration_55eea54b-4cd8-4ebd-a90d-a959aa46b365" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/SeparateAccountBalancesandChangesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#SeparateAccountBalancesandChangesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/SeparateAccountBalancesandChangesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityLineItems_a6eb738a-97e7-4a14-86ec-e02050fac956" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityTable_32455e05-b3b1-4c9f-a029-25d01a3ecad8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SeparateAccountLiabilityLineItems_a6eb738a-97e7-4a14-86ec-e02050fac956" xlink:to="loc_us-gaap_SeparateAccountLiabilityTable_32455e05-b3b1-4c9f-a029-25d01a3ecad8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_96f89b56-eaef-4ec9-b368-9dc1b0073e85" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SeparateAccountLiabilityTable_32455e05-b3b1-4c9f-a029-25d01a3ecad8" xlink:to="loc_srt_ProductOrServiceAxis_96f89b56-eaef-4ec9-b368-9dc1b0073e85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_96f89b56-eaef-4ec9-b368-9dc1b0073e85_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_96f89b56-eaef-4ec9-b368-9dc1b0073e85" xlink:to="loc_srt_ProductsAndServicesDomain_96f89b56-eaef-4ec9-b368-9dc1b0073e85_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5cde3576-ea54-43bb-8c92-0e33e120eefe" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_96f89b56-eaef-4ec9-b368-9dc1b0073e85" xlink:to="loc_srt_ProductsAndServicesDomain_5cde3576-ea54-43bb-8c92-0e33e120eefe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_5d32fd7f-ce58-488e-98c2-044de8490ce5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5cde3576-ea54-43bb-8c92-0e33e120eefe" xlink:to="loc_us-gaap_UniversalLifeMember_5d32fd7f-ce58-488e-98c2-044de8490ce5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityLineItems_a6eb738a-97e7-4a14-86ec-e02050fac956" xlink:to="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountsLiability_2f530046-eb1c-4ddf-9929-63613fe45a3a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:to="loc_us-gaap_SeparateAccountsLiability_2f530046-eb1c-4ddf-9929-63613fe45a3a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_SeparatedAccountLiabilityIncreaseDecreaseFromInterestCreditedBeforePolicyCharges_68966dbc-30df-4d8f-959c-7adc21def690" xlink:href="cinf-20250930.xsd#cinf_SeparatedAccountLiabilityIncreaseDecreaseFromInterestCreditedBeforePolicyCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:to="loc_cinf_SeparatedAccountLiabilityIncreaseDecreaseFromInterestCreditedBeforePolicyCharges_68966dbc-30df-4d8f-959c-7adc21def690" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityBenefitPayment_5f128cf3-9cb5-49f6-b275-9c3527c47ee2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityBenefitPayment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:to="loc_us-gaap_SeparateAccountLiabilityBenefitPayment_5f128cf3-9cb5-49f6-b275-9c3527c47ee2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange_b08b782b-4318-453e-bfe4-ba088deb145c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:to="loc_us-gaap_SeparateAccountLiabilityIncreaseDecreaseFromOtherChange_b08b782b-4318-453e-bfe4-ba088deb145c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountsLiability_598bc76f-55c3-4b9e-bd77-d69857929cdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountsLiability"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount_f711985c-20d0-4c9f-aa60-23a44af9ed46" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SeparateAccountLiabilityRollForward_422867be-6de2-45f6-855d-99c7934ecae1" xlink:to="loc_us-gaap_SeparateAccountLiabilityCashSurrenderValueAmount_f711985c-20d0-4c9f-aa60-23a44af9ed46" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/DeferredPolicyAcquisitionCostsDeferredPolicyAcquisitionCostsandAssetReconciliationDetail" xlink:type="simple" xlink:href="cinf-20250930.xsd#DeferredPolicyAcquisitionCostsDeferredPolicyAcquisitionCostsandAssetReconciliationDetail"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/DeferredPolicyAcquisitionCostsDeferredPolicyAcquisitionCostsandAssetReconciliationDetail" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsLineItems_6772c327-81cf-4ba0-843c-981cb4ecb550" xlink:href="cinf-20250930.xsd#cinf_ScheduleofDeferredPolicyAcquisitionCostsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsTable_54530ddd-05e5-4599-9ac7-9ffa47340980" xlink:href="cinf-20250930.xsd#cinf_ScheduleofDeferredPolicyAcquisitionCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsLineItems_6772c327-81cf-4ba0-843c-981cb4ecb550" xlink:to="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsTable_54530ddd-05e5-4599-9ac7-9ffa47340980" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_260ea4b6-a001-4c58-8c7a-8eb2dea94a00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsTable_54530ddd-05e5-4599-9ac7-9ffa47340980" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_260ea4b6-a001-4c58-8c7a-8eb2dea94a00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_260ea4b6-a001-4c58-8c7a-8eb2dea94a00_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_260ea4b6-a001-4c58-8c7a-8eb2dea94a00" xlink:to="loc_us-gaap_SegmentDomain_260ea4b6-a001-4c58-8c7a-8eb2dea94a00_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_8ed5fa83-2055-4bf1-b7c3-3ab1ac578946" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_260ea4b6-a001-4c58-8c7a-8eb2dea94a00" xlink:to="loc_us-gaap_SegmentDomain_8ed5fa83-2055-4bf1-b7c3-3ab1ac578946" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ConsolidatedPropertyAndCasualtyInsuranceMember_75528399-79a0-4b46-a313-174d618d93d1" xlink:href="cinf-20250930.xsd#cinf_ConsolidatedPropertyAndCasualtyInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8ed5fa83-2055-4bf1-b7c3-3ab1ac578946" xlink:to="loc_cinf_ConsolidatedPropertyAndCasualtyInsuranceMember_75528399-79a0-4b46-a313-174d618d93d1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_e4dc982e-f7e9-44d1-a7bd-e1ebab3872af" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_8ed5fa83-2055-4bf1-b7c3-3ab1ac578946" xlink:to="loc_cinf_LifeInsuranceMember_e4dc982e-f7e9-44d1-a7bd-e1ebab3872af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ed4071e3-f0f7-4ed6-b2ff-33ef56e4f2d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ScheduleofDeferredPolicyAcquisitionCostsLineItems_6772c327-81cf-4ba0-843c-981cb4ecb550" xlink:to="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ed4071e3-f0f7-4ed6-b2ff-33ef56e4f2d3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCosts_c5428939-9972-459a-92d0-4bfc533b1f96" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ed4071e3-f0f7-4ed6-b2ff-33ef56e4f2d3" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCosts_c5428939-9972-459a-92d0-4bfc533b1f96" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostsAdditions_914a6e6b-0596-4a73-9cce-a6ddfa2a4562" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostsAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ed4071e3-f0f7-4ed6-b2ff-33ef56e4f2d3" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCostsAdditions_914a6e6b-0596-4a73-9cce-a6ddfa2a4562" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense_e15a301a-12fc-4ae1-b446-79721e13e6c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ed4071e3-f0f7-4ed6-b2ff-33ef56e4f2d3" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense_e15a301a-12fc-4ae1-b446-79721e13e6c2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCosts_7dd4bf0d-964a-4a0c-bcd2-a8ae18bd2904" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/DeferredPolicyAcquisitionCostsLifeDeferredAcquisitionCostsRollforwardbyProductDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#DeferredPolicyAcquisitionCostsLifeDeferredAcquisitionCostsRollforwardbyProductDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/DeferredPolicyAcquisitionCostsLifeDeferredAcquisitionCostsRollforwardbyProductDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostLineItems_ada40c06-87a0-4142-99d9-e01c1e23261a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostTable_d2ce6b90-667e-468f-81a2-a1004123682f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DeferredPolicyAcquisitionCostLineItems_ada40c06-87a0-4142-99d9-e01c1e23261a" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCostTable_d2ce6b90-667e-468f-81a2-a1004123682f" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_3869c527-926d-4465-9f65-ff11f7cbc61f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DeferredPolicyAcquisitionCostTable_d2ce6b90-667e-468f-81a2-a1004123682f" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_3869c527-926d-4465-9f65-ff11f7cbc61f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_3869c527-926d-4465-9f65-ff11f7cbc61f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_3869c527-926d-4465-9f65-ff11f7cbc61f" xlink:to="loc_us-gaap_SegmentDomain_3869c527-926d-4465-9f65-ff11f7cbc61f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_33eb0b9c-81c3-487e-a9fb-208b4de41286" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_3869c527-926d-4465-9f65-ff11f7cbc61f" xlink:to="loc_us-gaap_SegmentDomain_33eb0b9c-81c3-487e-a9fb-208b4de41286" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_7a92d7ec-619e-4728-bbe7-ba014268dfcb" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_33eb0b9c-81c3-487e-a9fb-208b4de41286" xlink:to="loc_cinf_LifeInsuranceMember_7a92d7ec-619e-4728-bbe7-ba014268dfcb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_489bc0e2-99e7-4ecc-b322-a8133999370d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DeferredPolicyAcquisitionCostTable_d2ce6b90-667e-468f-81a2-a1004123682f" xlink:to="loc_srt_ProductOrServiceAxis_489bc0e2-99e7-4ecc-b322-a8133999370d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_489bc0e2-99e7-4ecc-b322-a8133999370d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_489bc0e2-99e7-4ecc-b322-a8133999370d" xlink:to="loc_srt_ProductsAndServicesDomain_489bc0e2-99e7-4ecc-b322-a8133999370d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_489bc0e2-99e7-4ecc-b322-a8133999370d" xlink:to="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TermLifeInsuranceMember_270f0bda-fe88-42ee-9d5b-17fd2390274f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TermLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:to="loc_us-gaap_TermLifeInsuranceMember_270f0bda-fe88-42ee-9d5b-17fd2390274f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WholeLifeInsuranceMember_8aaab760-10a3-40ad-9711-4f1881f8c33a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WholeLifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:to="loc_us-gaap_WholeLifeInsuranceMember_8aaab760-10a3-40ad-9711-4f1881f8c33a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFixedAnnuityMember_b6b6900d-4d57-407a-bef9-0450d2b52ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFixedAnnuityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:to="loc_us-gaap_DeferredFixedAnnuityMember_b6b6900d-4d57-407a-bef9-0450d2b52ab2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UniversalLifeMember_2dc31806-04cc-4769-927c-e3ae33440d45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UniversalLifeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_d17a605a-2240-4350-b2e3-b0a7ed56a1be" xlink:to="loc_us-gaap_UniversalLifeMember_2dc31806-04cc-4769-927c-e3ae33440d45" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ddad2b1f-d270-4cef-b1fc-fad510fe8f8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredPolicyAcquisitionCostLineItems_ada40c06-87a0-4142-99d9-e01c1e23261a" xlink:to="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ddad2b1f-d270-4cef-b1fc-fad510fe8f8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCosts_c90ffac6-edbd-457c-8b27-fbcc0a5e738e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ddad2b1f-d270-4cef-b1fc-fad510fe8f8a" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCosts_c90ffac6-edbd-457c-8b27-fbcc0a5e738e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostsAdditions_0489d50a-f62e-4fe9-85ec-3e19c08606fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostsAdditions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ddad2b1f-d270-4cef-b1fc-fad510fe8f8a" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCostsAdditions_0489d50a-f62e-4fe9-85ec-3e19c08606fa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense_0ffae101-dff9-4326-88b8-171950bf42ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_MovementAnalysisOfDeferredPolicyAcquisitionCostsRollForward_ddad2b1f-d270-4cef-b1fc-fad510fe8f8a" xlink:to="loc_us-gaap_DeferredPolicyAcquisitionCostAmortizationExpense_0ffae101-dff9-4326-88b8-171950bf42ab" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredPolicyAcquisitionCosts_9b67df13-2c96-4646-80e0-57dc949271b3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredPolicyAcquisitionCosts"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/AccumulatedOtherComprehensiveIncomeAOCIDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#AccumulatedOtherComprehensiveIncomeAOCIDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/AccumulatedOtherComprehensiveIncomeAOCIDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeLineItems_1ad5a229-3c13-47a4-9301-98bb34a78953" xlink:href="cinf-20250930.xsd#cinf_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_9c91c94b-0494-4e91-86ba-b9c78157b7c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cinf_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeLineItems_1ad5a229-3c13-47a4-9301-98bb34a78953" xlink:to="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_9c91c94b-0494-4e91-86ba-b9c78157b7c9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_5bab0a76-a199-41d6-bab6-cc1ecbdb556d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeTable_9c91c94b-0494-4e91-86ba-b9c78157b7c9" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_5bab0a76-a199-41d6-bab6-cc1ecbdb556d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_5bab0a76-a199-41d6-bab6-cc1ecbdb556d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5bab0a76-a199-41d6-bab6-cc1ecbdb556d" xlink:to="loc_us-gaap_EquityComponentDomain_5bab0a76-a199-41d6-bab6-cc1ecbdb556d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_5bab0a76-a199-41d6-bab6-cc1ecbdb556d" xlink:to="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_aa424de1-263e-4450-bcaa-02d985dbc707" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:to="loc_us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember_aa424de1-263e-4450-bcaa-02d985dbc707" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_9c393af8-1555-431e-9ef5-8d6753b848d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_9c393af8-1555-431e-9ef5-8d6753b848d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AccumulatedNetUnrealizedGainLossOnLifePolicyReservesReinsuranceRecoverableAndOtherMember_0c0c4e2f-6c60-443b-999b-568b4fdb8d23" xlink:href="cinf-20250930.xsd#cinf_AccumulatedNetUnrealizedGainLossOnLifePolicyReservesReinsuranceRecoverableAndOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:to="loc_cinf_AccumulatedNetUnrealizedGainLossOnLifePolicyReservesReinsuranceRecoverableAndOtherMember_0c0c4e2f-6c60-443b-999b-568b4fdb8d23" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_995c6c1c-1a17-4c9f-8cd8-310b62e37609" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_4e27c3a8-871f-4db4-b8ae-6e4ce19a59db" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_995c6c1c-1a17-4c9f-8cd8-310b62e37609" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward_f3ec423b-545e-4429-bb6f-79a16569b949" xlink:href="cinf-20250930.xsd#cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ReclassificationOutOfAccumulatedOtherComprehensiveIncomeLineItems_1ad5a229-3c13-47a4-9301-98bb34a78953" xlink:to="loc_cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward_f3ec423b-545e-4429-bb6f-79a16569b949" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward_f3ec423b-545e-4429-bb6f-79a16569b949" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1_f2d136e9-46ab-40f9-9ed8-b664b9c6ac8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1_f2d136e9-46ab-40f9-9ed8-b664b9c6ac8b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_06fe0760-3052-438e-8bd1-b83d85da5180" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax_06fe0760-3052-438e-8bd1-b83d85da5180" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_e05b7b01-ef80-4dae-b0f4-5d2e9e906b91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax_e05b7b01-ef80-4dae-b0f4-5d2e9e906b91" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_224f6202-e05e-4ada-9292-84570990889d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPortionAttributableToParent_224f6202-e05e-4ada-9292-84570990889d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentBeforeTax_fbb86df5-fdf3-4951-9b6f-787c7ae31001" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentBeforeTax_fbb86df5-fdf3-4951-9b6f-787c7ae31001" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_a5fd3c8f-4be1-4c6f-8c90-4531a5be42f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentBeforeTax_a5fd3c8f-4be1-4c6f-8c90-4531a5be42f2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherBeforeTax_14ab5650-b093-4f65-a7c2-6afd722da61f" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherBeforeTax_14ab5650-b093-4f65-a7c2-6afd722da61f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossBeforeTax_454abb2a-8af5-4052-8a67-2f16f78655a8" xlink:href="cinf-20250930.xsd#cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossBeforeTaxPeriodIncreaseDecreaseAbstract_004eaf22-c553-43ac-8026-acb16aea3f2b" xlink:to="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossBeforeTax_454abb2a-8af5-4052-8a67-2f16f78655a8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1_6749db4b-f85f-481e-89cf-0dcaf2cbda25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossBeforeTax1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:href="cinf-20250930.xsd#cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward_f3ec423b-545e-4429-bb6f-79a16569b949" xlink:to="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTax_0d561ef3-6493-4cb4-bf24-98fb843055de" xlink:href="cinf-20250930.xsd#cinf_AccumulatedOtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTax_0d561ef3-6493-4cb4-bf24-98fb843055de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_0f7ff7bf-f6d3-468d-b45b-d7faa865bcc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax_0f7ff7bf-f6d3-468d-b45b-d7faa865bcc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ReclassificationfromAccumulatedOtherComprehensiveIncomeCurrentPeriodTax_efe67701-caf1-4beb-80e2-52c583a8496e" xlink:href="cinf-20250930.xsd#cinf_ReclassificationfromAccumulatedOtherComprehensiveIncomeCurrentPeriodTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_cinf_ReclassificationfromAccumulatedOtherComprehensiveIncomeCurrentPeriodTax_efe67701-caf1-4beb-80e2-52c583a8496e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_cd000ba8-f17a-4f6d-8c86-cfa0d7a9fdcc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_cd000ba8-f17a-4f6d-8c86-cfa0d7a9fdcc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentTax_88e54f5f-a0c0-4f27-ae66-8233f4be16cd" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentTax_88e54f5f-a0c0-4f27-ae66-8233f4be16cd" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_ac739199-6bf4-4811-95b4-7330478df43b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax_ac739199-6bf4-4811-95b4-7330478df43b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherTax_e8952960-0902-44fd-a5d6-28e4cef8ac2d" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherTax_e8952960-0902-44fd-a5d6-28e4cef8ac2d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossTax_ceb69b65-0564-46e7-b7f0-3bee9a7e15e1" xlink:href="cinf-20250930.xsd#cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTaxAbstract_a1b75bcd-e77e-48f2-884b-38bed2074388" xlink:to="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossTax_ceb69b65-0564-46e7-b7f0-3bee9a7e15e1" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_AccumulatedOtherComprehensiveIncomeLossTax_64463dc2-295b-4ca0-8607-ad572b91c4fe" xlink:href="cinf-20250930.xsd#cinf_AccumulatedOtherComprehensiveIncomeLossTax"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ChangeInAccumulatedOtherComprehensiveIncomeRollForward_f3ec423b-545e-4429-bb6f-79a16569b949" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_fd9cc9a7-02ae-426f-a5f6-9690724c1ade" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_us-gaap_StockholdersEquity_fd9cc9a7-02ae-426f-a5f6-9690724c1ade" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_5ece061f-987a-4405-8756-b921c9b976f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax_5ece061f-987a-4405-8756-b921c9b976f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_a9c059af-63af-415b-ac32-3da801e11fa1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax_a9c059af-63af-415b-ac32-3da801e11fa1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_111fcbbe-4f01-47ca-8c73-a13e15d65174" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_111fcbbe-4f01-47ca-8c73-a13e15d65174" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentNetOfTax_662d6347-5aa4-4dd3-b87a-cdfd0e72f2c7" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_cinf_OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAndOtherAssetsAdjustmentNetOfTax_662d6347-5aa4-4dd3-b87a-cdfd0e72f2c7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_30d59e45-8674-4c57-8eee-dfb7dc972c25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax_30d59e45-8674-4c57-8eee-dfb7dc972c25" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherNetOfTax_90c73a4b-960a-4e54-baa0-99eb347029f0" xlink:href="cinf-20250930.xsd#cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_cinf_OtherComprehensiveIncomeLossLifePolicyReservesReinsuranceRecoverableAndOtherNetOfTax_90c73a4b-960a-4e54-baa0-99eb347029f0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossNetOfTax_e7b2cc5a-74b6-4565-ac06-ce2ffc20293c" xlink:href="cinf-20250930.xsd#cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTaxAbstract_4eb510cd-3a3b-4aa7-803a-271a87491342" xlink:to="loc_cinf_IncreaseDecreaseInOtherComprehensiveIncomeLossNetOfTax_e7b2cc5a-74b6-4565-ac06-ce2ffc20293c" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_5f8b2e82-55e8-449d-b013-faeb7b98bf89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/ReinsuranceConsolidatedPropertyCasualtyInsuranceAssumedandCededBusinessDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#ReinsuranceConsolidatedPropertyCasualtyInsuranceAssumedandCededBusinessDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/ReinsuranceConsolidatedPropertyCasualtyInsuranceAssumedandCededBusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:href="cinf-20250930.xsd#cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessTable_8acf04e5-345c-490d-93f1-ca0af409ff4b" xlink:href="cinf-20250930.xsd#cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessTable_8acf04e5-345c-490d-93f1-ca0af409ff4b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_7cc24e3c-8abb-4cab-8c29-edc7dc44897c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessTable_8acf04e5-345c-490d-93f1-ca0af409ff4b" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_7cc24e3c-8abb-4cab-8c29-edc7dc44897c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_7cc24e3c-8abb-4cab-8c29-edc7dc44897c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7cc24e3c-8abb-4cab-8c29-edc7dc44897c" xlink:to="loc_us-gaap_SegmentDomain_7cc24e3c-8abb-4cab-8c29-edc7dc44897c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_616777f3-7717-4f9e-a366-2b58ef26f37d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_7cc24e3c-8abb-4cab-8c29-edc7dc44897c" xlink:to="loc_us-gaap_SegmentDomain_616777f3-7717-4f9e-a366-2b58ef26f37d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ConsolidatedPropertyAndCasualtyInsuranceMember_fa8d645d-b0d7-45f8-a12f-21bf905dd099" xlink:href="cinf-20250930.xsd#cinf_ConsolidatedPropertyAndCasualtyInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_616777f3-7717-4f9e-a366-2b58ef26f37d" xlink:to="loc_cinf_ConsolidatedPropertyAndCasualtyInsuranceMember_fa8d645d-b0d7-45f8-a12f-21bf905dd099" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DirectPremiumsWritten_b006d90b-cd94-4055-ab74-0cbbbc567fb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsWritten"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_DirectPremiumsWritten_b006d90b-cd94-4055-ab74-0cbbbc567fb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssumedPremiumsWritten_6577f8ce-cdb6-426c-ad28-701871f85342" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssumedPremiumsWritten"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_AssumedPremiumsWritten_6577f8ce-cdb6-426c-ad28-701871f85342" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CededPremiumsWritten_2e3731f7-37d2-4d05-83e9-003b1222b288" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsWritten"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_CededPremiumsWritten_2e3731f7-37d2-4d05-83e9-003b1222b288" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInPropertyAndCasualtyInsuranceLiabilities_d1c64b29-6b66-4090-978c-cb8581fda11d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInPropertyAndCasualtyInsuranceLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_IncreaseDecreaseInPropertyAndCasualtyInsuranceLiabilities_d1c64b29-6b66-4090-978c-cb8581fda11d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DirectPremiumsEarned_1c3f442e-163c-482f-a076-825d12d856fe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_DirectPremiumsEarned_1c3f442e-163c-482f-a076-825d12d856fe" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssumedPremiumsEarned_03f1dab2-a38a-41bf-a52c-140c3b96b0c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssumedPremiumsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_AssumedPremiumsEarned_03f1dab2-a38a-41bf-a52c-140c3b96b0c7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CededPremiumsEarned_bae38698-3699-4c00-adc3-1796d111ce08" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_CededPremiumsEarned_bae38698-3699-4c00-adc3-1796d111ce08" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_e5c4a44b-f520-4c29-986e-49243e98832e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_PremiumsEarnedNet_e5c4a44b-f520-4c29-986e-49243e98832e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredGross_3b5a73d0-ae32-4f30-ba7a-5313e9d4f400" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredGross_3b5a73d0-ae32-4f30-ba7a-5313e9d4f400" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed_1ba5ad28-b65f-4546-9c1e-18a98209258c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountAssumed_1ba5ad28-b65f-4546-9c1e-18a98209258c" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded_03e91b4b-124d-4c31-9d99-b3352aff6d45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded_03e91b4b-124d-4c31-9d99-b3352aff6d45" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_a77b1e49-ccca-4878-804a-2533df4a01c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_PropertyCasualtyInsurancePremiumsWrittenOnAssumedAndCededBusinessLineItems_0c9b33bf-6ad5-4a9f-879a-a8f3b6ea2a59" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_a77b1e49-ccca-4878-804a-2533df4a01c5" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/ReinsuranceLifeInsuranceCededBusinessDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#ReinsuranceLifeInsuranceCededBusinessDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/ReinsuranceLifeInsuranceCededBusinessDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_3ef0faea-6b1e-42c3-88dc-9fdf8ec6837d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_3ef0faea-6b1e-42c3-88dc-9fdf8ec6837d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_0fe97b6b-5c49-4960-845f-edf8b45e830e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_3ef0faea-6b1e-42c3-88dc-9fdf8ec6837d" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_0fe97b6b-5c49-4960-845f-edf8b45e830e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0fe97b6b-5c49-4960-845f-edf8b45e830e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0fe97b6b-5c49-4960-845f-edf8b45e830e" xlink:to="loc_us-gaap_SegmentDomain_0fe97b6b-5c49-4960-845f-edf8b45e830e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_0385d97f-1b45-4acb-8456-f177ae3b2afc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_0fe97b6b-5c49-4960-845f-edf8b45e830e" xlink:to="loc_us-gaap_SegmentDomain_0385d97f-1b45-4acb-8456-f177ae3b2afc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_d40987a8-3067-4541-803b-962ef8714696" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_0385d97f-1b45-4acb-8456-f177ae3b2afc" xlink:to="loc_cinf_LifeInsuranceMember_d40987a8-3067-4541-803b-962ef8714696" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DirectPremiumsEarned_350a2298-37a1-43de-88bf-4d1a00fb9e32" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DirectPremiumsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_DirectPremiumsEarned_350a2298-37a1-43de-88bf-4d1a00fb9e32" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CededPremiumsEarned_796f5f93-1f6b-47f4-868e-7a176ce16423" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CededPremiumsEarned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_CededPremiumsEarned_796f5f93-1f6b-47f4-868e-7a176ce16423" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_614145d7-f8c0-4aad-a130-c96c2cffcf03" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_PremiumsEarnedNet_614145d7-f8c0-4aad-a130-c96c2cffcf03" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredGross_550d2882-d23e-4cb3-ac4d-ef88f530541c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredGross_550d2882-d23e-4cb3-ac4d-ef88f530541c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded_30c6476a-3ff2-4412-910c-47266786d851" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_ReinsuranceEffectOnClaimsAndBenefitsIncurredAmountCeded_30c6476a-3ff2-4412-910c-47266786d851" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_48ac82c0-8946-4008-93c8-dbd09acda416" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_5df63a19-3140-4681-899a-4e4ef2291309" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_48ac82c0-8946-4008-93c8-dbd09acda416" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/ReinsuranceNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#ReinsuranceNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/ReinsuranceNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_c697b30a-0ec3-417a-a1c0-3caa2142286f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_4c748823-7d9f-418f-b3ec-5679b75fbbe2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_c697b30a-0ec3-417a-a1c0-3caa2142286f" xlink:to="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_4c748823-7d9f-418f-b3ec-5679b75fbbe2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5093d7e5-2c62-41a8-a406-fd412d4508fd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentTable_4c748823-7d9f-418f-b3ec-5679b75fbbe2" xlink:to="loc_srt_ProductOrServiceAxis_5093d7e5-2c62-41a8-a406-fd412d4508fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5093d7e5-2c62-41a8-a406-fd412d4508fd_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5093d7e5-2c62-41a8-a406-fd412d4508fd" xlink:to="loc_srt_ProductsAndServicesDomain_5093d7e5-2c62-41a8-a406-fd412d4508fd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_bee7257a-6afe-4877-96f4-b49f93eddce8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5093d7e5-2c62-41a8-a406-fd412d4508fd" xlink:to="loc_srt_ProductsAndServicesDomain_bee7257a-6afe-4877-96f4-b49f93eddce8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember_303502b4-1d18-4012-a870-272e929e723f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_bee7257a-6afe-4877-96f4-b49f93eddce8" xlink:to="loc_us-gaap_PropertyLiabilityAndCasualtyInsuranceSegmentMember_303502b4-1d18-4012-a870-272e929e723f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts_5d24d6ee-7cb6-47d4-9749-25d3a954dd8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ReinsurancePremiumsForInsuranceCompaniesByProductSegmentLineItems_c697b30a-0ec3-417a-a1c0-3caa2142286f" xlink:to="loc_us-gaap_PremiumsReceivableAllowanceForDoubtfulAccounts_5d24d6ee-7cb6-47d4-9749-25d3a954dd8d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyLineItems_46081c5e-7493-4c9a-af71-0a23cd7f22ea" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxContingencyTable_9d2f2da1-f4c3-42bb-9311-37ab85fbcd42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxContingencyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_46081c5e-7493-4c9a-af71-0a23cd7f22ea" xlink:to="loc_us-gaap_IncomeTaxContingencyTable_9d2f2da1-f4c3-42bb-9311-37ab85fbcd42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_6d0a5a43-65cb-4c61-89a4-7a336f16628a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_9d2f2da1-f4c3-42bb-9311-37ab85fbcd42" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_6d0a5a43-65cb-4c61-89a4-7a336f16628a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d0a5a43-65cb-4c61-89a4-7a336f16628a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6d0a5a43-65cb-4c61-89a4-7a336f16628a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_6d0a5a43-65cb-4c61-89a4-7a336f16628a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ab1b699e-aa2c-46b2-a227-e7c9c3c9c261" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_6d0a5a43-65cb-4c61-89a4-7a336f16628a" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ab1b699e-aa2c-46b2-a227-e7c9c3c9c261" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_MSPUnderwritingLimitedMember_218f0900-d26b-463a-b395-ecc53d926b34" xlink:href="cinf-20250930.xsd#cinf_MSPUnderwritingLimitedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_ab1b699e-aa2c-46b2-a227-e7c9c3c9c261" xlink:to="loc_cinf_MSPUnderwritingLimitedMember_218f0900-d26b-463a-b395-ecc53d926b34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionAxis_ba42e437-c54c-4473-9d07-d460c7ff955d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxContingencyTable_9d2f2da1-f4c3-42bb-9311-37ab85fbcd42" xlink:to="loc_us-gaap_GeographicDistributionAxis_ba42e437-c54c-4473-9d07-d460c7ff955d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_ba42e437-c54c-4473-9d07-d460c7ff955d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GeographicDistributionAxis_ba42e437-c54c-4473-9d07-d460c7ff955d" xlink:to="loc_us-gaap_GeographicDistributionDomain_ba42e437-c54c-4473-9d07-d460c7ff955d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomain_9dbacdab-a2f0-4b7b-ae13-9f0180fe3fb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GeographicDistributionAxis_ba42e437-c54c-4473-9d07-d460c7ff955d" xlink:to="loc_us-gaap_GeographicDistributionDomain_9dbacdab-a2f0-4b7b-ae13-9f0180fe3fb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionDomesticMember_a6afc7c4-cac7-447d-858f-58b626611e86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionDomesticMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_9dbacdab-a2f0-4b7b-ae13-9f0180fe3fb0" xlink:to="loc_us-gaap_GeographicDistributionDomesticMember_a6afc7c4-cac7-447d-858f-58b626611e86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeographicDistributionForeignMember_ed57e250-3fb9-49a2-b6de-2595c2a60872" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeographicDistributionForeignMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GeographicDistributionDomain_9dbacdab-a2f0-4b7b-ae13-9f0180fe3fb0" xlink:to="loc_us-gaap_GeographicDistributionForeignMember_ed57e250-3fb9-49a2-b6de-2595c2a60872" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_dbb411da-5cfc-4202-b015-7e8c8247d9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_46081c5e-7493-4c9a-af71-0a23cd7f22ea" xlink:to="loc_us-gaap_EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate_dbb411da-5cfc-4202-b015-7e8c8247d9b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_f1817fd2-75cb-4d2d-849f-f79932ff1d03" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_46081c5e-7493-4c9a-af71-0a23cd7f22ea" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_f1817fd2-75cb-4d2d-849f-f79932ff1d03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_ff66eda6-9016-429b-a43e-5e5b7ce182b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxContingencyLineItems_46081c5e-7493-4c9a-af71-0a23cd7f22ea" xlink:to="loc_us-gaap_OperatingLossCarryforwards_ff66eda6-9016-429b-a43e-5e5b7ce182b8" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/NetIncomePerCommonShareCalculationsforBasicandDilutedEarningsPerShareDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#NetIncomePerCommonShareCalculationsforBasicandDilutedEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/NetIncomePerCommonShareCalculationsforBasicandDilutedEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_56e95599-216d-475c-991f-f0de8bee2511" xlink:href="cinf-20250930.xsd#cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_272b6509-8025-4ef1-ad1f-217ad2c7cb0b" xlink:href="cinf-20250930.xsd#cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_56e95599-216d-475c-991f-f0de8bee2511" xlink:to="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_272b6509-8025-4ef1-ad1f-217ad2c7cb0b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_1b7e95a8-3c64-4684-8965-8920c2657c61" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassTable_272b6509-8025-4ef1-ad1f-217ad2c7cb0b" xlink:to="loc_us-gaap_AwardTypeAxis_1b7e95a8-3c64-4684-8965-8920c2657c61" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1b7e95a8-3c64-4684-8965-8920c2657c61_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_1b7e95a8-3c64-4684-8965-8920c2657c61" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_1b7e95a8-3c64-4684-8965-8920c2657c61_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_165c6c67-c1bf-48c1-9acc-b4315594c463" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_1b7e95a8-3c64-4684-8965-8920c2657c61" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_165c6c67-c1bf-48c1-9acc-b4315594c463" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_f739b3f1-142d-4f8f-81a0-72a5552a1caf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_165c6c67-c1bf-48c1-9acc-b4315594c463" xlink:to="loc_us-gaap_EmployeeStockOptionMember_f739b3f1-142d-4f8f-81a0-72a5552a1caf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockUnitsRSUMember_e83481e3-022c-4385-a48e-45abe119aa90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockUnitsRSUMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_165c6c67-c1bf-48c1-9acc-b4315594c463" xlink:to="loc_us-gaap_RestrictedStockUnitsRSUMember_e83481e3-022c-4385-a48e-45abe119aa90" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAbstract_bb48cb92-e618-44cc-8b4e-cb7ceafb7373" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLossAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_56e95599-216d-475c-991f-f0de8bee2511" xlink:to="loc_us-gaap_NetIncomeLossAbstract_bb48cb92-e618-44cc-8b4e-cb7ceafb7373" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_f9df1e02-1466-4b35-91d0-04de6a1b871a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_NetIncomeLossAbstract_bb48cb92-e618-44cc-8b4e-cb7ceafb7373" xlink:to="loc_us-gaap_NetIncomeLoss_f9df1e02-1466-4b35-91d0-04de6a1b871a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_096a1bba-b769-4b11-b5b1-d8309252d328" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_56e95599-216d-475c-991f-f0de8bee2511" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_096a1bba-b769-4b11-b5b1-d8309252d328" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_190325ed-a98e-4eea-b444-b2ea4ca7a864" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_096a1bba-b769-4b11-b5b1-d8309252d328" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_190325ed-a98e-4eea-b444-b2ea4ca7a864" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_6b9132d1-33b4-4d72-825b-e66268b3ffeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_096a1bba-b769-4b11-b5b1-d8309252d328" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_6b9132d1-33b4-4d72-825b-e66268b3ffeb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_06ac50c4-759e-41ba-b933-faba7f111edf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_096a1bba-b769-4b11-b5b1-d8309252d328" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_06ac50c4-759e-41ba-b933-faba7f111edf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareReconciliationAbstract_1cef1d5f-3f02-4efd-a778-1d43c6a9127a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareReconciliationAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_cinf_ScheduleOfEarningsPerShareBasicAndDilutedByCommonClassLineItems_56e95599-216d-475c-991f-f0de8bee2511" xlink:to="loc_us-gaap_EarningsPerShareReconciliationAbstract_1cef1d5f-3f02-4efd-a778-1d43c6a9127a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_fe24a173-9d84-455e-a62a-516896d07828" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_1cef1d5f-3f02-4efd-a778-1d43c6a9127a" xlink:to="loc_us-gaap_EarningsPerShareBasic_fe24a173-9d84-455e-a62a-516896d07828" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_05a3ab93-4594-4607-b404-31f62dbb7451" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_1cef1d5f-3f02-4efd-a778-1d43c6a9127a" xlink:to="loc_us-gaap_EarningsPerShareDiluted_05a3ab93-4594-4607-b404-31f62dbb7451" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_93fa5e7e-85e5-4dbb-a9fd-47ecd388c8d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareReconciliationAbstract_1cef1d5f-3f02-4efd-a778-1d43c6a9127a" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_93fa5e7e-85e5-4dbb-a9fd-47ecd388c8d3" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/EmployeeRetirementBenefitsComponentsofNetPeriodicCostsforQualifiedandSupplementalPensionPlansDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#EmployeeRetirementBenefitsComponentsofNetPeriodicCostsforQualifiedandSupplementalPensionPlansDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/EmployeeRetirementBenefitsComponentsofNetPeriodicCostsforQualifiedandSupplementalPensionPlansDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_1f2016d9-84a1-45ac-a2f6-1186600e8ae4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_1f2016d9-84a1-45ac-a2f6-1186600e8ae4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_664f242a-b995-4250-be01-d64e3db87492" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_1f2016d9-84a1-45ac-a2f6-1186600e8ae4" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_664f242a-b995-4250-be01-d64e3db87492" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_664f242a-b995-4250-be01-d64e3db87492_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_664f242a-b995-4250-be01-d64e3db87492" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_664f242a-b995-4250-be01-d64e3db87492_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_385e0bfd-0ba2-491f-b424-545bffd6470a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_664f242a-b995-4250-be01-d64e3db87492" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_385e0bfd-0ba2-491f-b424-545bffd6470a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_fe323e55-f3b0-45f9-84c2-a02b5dcc0e76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_385e0bfd-0ba2-491f-b424-545bffd6470a" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_fe323e55-f3b0-45f9-84c2-a02b5dcc0e76" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanServiceCost_c82b1901-2612-448c-b408-4bfc4ecb9873" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanServiceCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_DefinedBenefitPlanServiceCost_c82b1901-2612-448c-b408-4bfc4ecb9873" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanInterestCost_ebe3b0cc-c6f1-48eb-b574-cbb424bfcf2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanInterestCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_DefinedBenefitPlanInterestCost_ebe3b0cc-c6f1-48eb-b574-cbb424bfcf2d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_6b5ceabf-53ab-4965-b494-27ced66dd694" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_DefinedBenefitPlanExpectedReturnOnPlanAssets_6b5ceabf-53ab-4965-b494-27ced66dd694" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_0e4f8222-bd4f-4187-84ca-530bdebb8e1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_DefinedBenefitPlanAmortizationOfGainsLosses_0e4f8222-bd4f-4187-84ca-530bdebb8e1b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_DefinedBenefitPlanNonServiceCostBenefit_70be73ee-27b4-48e5-b33a-988670c362dd" xlink:href="cinf-20250930.xsd#cinf_DefinedBenefitPlanNonServiceCostBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_cinf_DefinedBenefitPlanNonServiceCostBenefit_70be73ee-27b4-48e5-b33a-988670c362dd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_746907f4-cff7-4290-b2b4-293f7443982c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_e296d590-8fb1-4955-b114-0c0321f6b1f3" xlink:to="loc_us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost_746907f4-cff7-4290-b2b4-293f7443982c" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/EmployeeRetirementBenefitsDefinedContributionPlanNarrativeDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#EmployeeRetirementBenefitsDefinedContributionPlanNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/EmployeeRetirementBenefitsDefinedContributionPlanNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d024eadd-764f-4d25-8370-740e7d0267ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedBenefitPlanDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fb63736a-8af2-4b0d-a4e9-2c7d58bded1b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d024eadd-764f-4d25-8370-740e7d0267ab" xlink:to="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fb63736a-8af2-4b0d-a4e9-2c7d58bded1b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeAxis_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfDefinedBenefitPlansDisclosuresTable_fb63736a-8af2-4b0d-a4e9-2c7d58bded1b" xlink:to="loc_us-gaap_RetirementPlanTypeAxis_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetirementPlanTypeDomain_796bc18d-02dd-4447-833a-c579de1d006e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetirementPlanTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RetirementPlanTypeAxis_3a3a57c4-2f57-4694-a576-4ca9bd1b30a4" xlink:to="loc_us-gaap_RetirementPlanTypeDomain_796bc18d-02dd-4447-833a-c579de1d006e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionPlansDefinedBenefitMember_98feb3ec-f793-4aef-9506-464156513c31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionPlansDefinedBenefitMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RetirementPlanTypeDomain_796bc18d-02dd-4447-833a-c579de1d006e" xlink:to="loc_us-gaap_PensionPlansDefinedBenefitMember_98feb3ec-f793-4aef-9506-464156513c31" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_58620eb7-e2e2-46c1-b86a-c26daaee6a1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d024eadd-764f-4d25-8370-740e7d0267ab" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_58620eb7-e2e2-46c1-b86a-c26daaee6a1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PensionContributions_56e0c4ec-82cf-4ca2-93a8-f99033d42e41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PensionContributions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DefinedBenefitPlanDisclosureLineItems_d024eadd-764f-4d25-8370-740e7d0267ab" xlink:to="loc_us-gaap_PensionContributions_56e0c4ec-82cf-4ca2-93a8-f99033d42e41" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/SegmentInformationSegmentIncomeLossBeforeIncomeTaxesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#SegmentInformationSegmentIncomeLossBeforeIncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/SegmentInformationSegmentIncomeLossBeforeIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_50fb850f-c1c5-4e1d-b12d-8196972e7f5d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_50fb850f-c1c5-4e1d-b12d-8196972e7f5d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_66c3b138-ed99-4b8b-ab3f-b59b6da73557" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_50fb850f-c1c5-4e1d-b12d-8196972e7f5d" xlink:to="loc_srt_ConsolidationItemsAxis_66c3b138-ed99-4b8b-ab3f-b59b6da73557" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_66c3b138-ed99-4b8b-ab3f-b59b6da73557_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_66c3b138-ed99-4b8b-ab3f-b59b6da73557" xlink:to="loc_srt_ConsolidationItemsDomain_66c3b138-ed99-4b8b-ab3f-b59b6da73557_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_d0061489-050c-4836-be0c-2cd722aa768a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_66c3b138-ed99-4b8b-ab3f-b59b6da73557" xlink:to="loc_srt_ConsolidationItemsDomain_d0061489-050c-4836-be0c-2cd722aa768a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_72a5f093-4c20-49c0-9205-dcb1505fee78" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_d0061489-050c-4836-be0c-2cd722aa768a" xlink:to="loc_us-gaap_OperatingSegmentsMember_72a5f093-4c20-49c0-9205-dcb1505fee78" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_02c25352-df10-4606-84b7-5fad215de5af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_50fb850f-c1c5-4e1d-b12d-8196972e7f5d" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_02c25352-df10-4606-84b7-5fad215de5af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_02c25352-df10-4606-84b7-5fad215de5af_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_02c25352-df10-4606-84b7-5fad215de5af" xlink:to="loc_us-gaap_SegmentDomain_02c25352-df10-4606-84b7-5fad215de5af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_02c25352-df10-4606-84b7-5fad215de5af" xlink:to="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_CommercialLinesInsuranceMember_c7606b1e-36e9-401b-9e69-f8db44963230" xlink:href="cinf-20250930.xsd#cinf_CommercialLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:to="loc_cinf_CommercialLinesInsuranceMember_c7606b1e-36e9-401b-9e69-f8db44963230" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_PersonalLinesInsuranceMember_24ff7de8-8a16-4134-b10c-843a7cd1ec9a" xlink:href="cinf-20250930.xsd#cinf_PersonalLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:to="loc_cinf_PersonalLinesInsuranceMember_24ff7de8-8a16-4134-b10c-843a7cd1ec9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_ExcessandSurplusLinesInsuranceMember_06b63c3c-62e9-46e1-89de-6bac4832f99a" xlink:href="cinf-20250930.xsd#cinf_ExcessandSurplusLinesInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:to="loc_cinf_ExcessandSurplusLinesInsuranceMember_06b63c3c-62e9-46e1-89de-6bac4832f99a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_c52fd99d-16bc-428b-b681-62a7dec5f26e" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:to="loc_cinf_LifeInsuranceMember_c52fd99d-16bc-428b-b681-62a7dec5f26e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentSegmentOfCINFMember_690b2c07-1df8-448c-ae14-39bb0a5badc2" xlink:href="cinf-20250930.xsd#cinf_InvestmentSegmentOfCINFMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_00a852da-0869-4120-925b-a6c6b352d8d5" xlink:to="loc_cinf_InvestmentSegmentOfCINFMember_690b2c07-1df8-448c-ae14-39bb0a5badc2" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_2fa9e398-9019-4746-8ec3-156768f3f079" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_PremiumsEarnedNet_2fa9e398-9019-4746-8ec3-156768f3f079" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InsuranceCommissionsAndFees_81f3872c-cae3-473b-b707-3dc76ac5d78c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InsuranceCommissionsAndFees"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_InsuranceCommissionsAndFees_81f3872c-cae3-473b-b707-3dc76ac5d78c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentIncome_d0b66e08-5e44-4cce-be64-2f8bf62a644f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_NetInvestmentIncome_d0b66e08-5e44-4cce-be64-2f8bf62a644f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainLossOnInvestments_3eedbf29-715e-4c14-adef-9bdd3fa86dd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainLossOnInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_GainLossOnInvestments_3eedbf29-715e-4c14-adef-9bdd3fa86dd6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_9634344c-739b-426d-b3b0-3b72b2a6075b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_Revenues_9634344c-739b-426d-b3b0-3b72b2a6075b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_0e8aa480-65c7-4ea6-9a8c-002979f524c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_0e8aa480-65c7-4ea6-9a8c-002979f524c8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_b6963452-504a-43ec-91d2-c310d983d438" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_InvestmentIncomeInterest_b6963452-504a-43ec-91d2-c310d983d438" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_UnderwritingAcquisitionAndInsuranceExpenses_e2cd7f2a-1464-40c6-92b4-133ddf30dcbf" xlink:href="cinf-20250930.xsd#cinf_UnderwritingAcquisitionAndInsuranceExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_cinf_UnderwritingAcquisitionAndInsuranceExpenses_e2cd7f2a-1464-40c6-92b4-133ddf30dcbf" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_32036d11-c277-4cf1-a3cb-ae116b208793" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_7e9fbc15-a021-46d8-ad8f-a3e9d036eff2" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments_32036d11-c277-4cf1-a3cb-ae116b208793" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/SegmentInformationReconciliationtoConsolidatedIncomeBeforeIncomeTaxesDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#SegmentInformationReconciliationtoConsolidatedIncomeBeforeIncomeTaxesDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/SegmentInformationReconciliationtoConsolidatedIncomeBeforeIncomeTaxesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_f54d8ee9-a125-483a-84a4-833b4bb7c77b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_f54d8ee9-a125-483a-84a4-833b4bb7c77b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_db0c9404-dc1b-43b2-99b8-829659074089" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfOperatingProfitLossFromSegmentsToConsolidatedTable_f54d8ee9-a125-483a-84a4-833b4bb7c77b" xlink:to="loc_srt_ConsolidationItemsAxis_db0c9404-dc1b-43b2-99b8-829659074089" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_db0c9404-dc1b-43b2-99b8-829659074089_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_db0c9404-dc1b-43b2-99b8-829659074089" xlink:to="loc_srt_ConsolidationItemsDomain_db0c9404-dc1b-43b2-99b8-829659074089_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_f2cf1127-6b69-488c-b951-160495ac6a32" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_db0c9404-dc1b-43b2-99b8-829659074089" xlink:to="loc_srt_ConsolidationItemsDomain_f2cf1127-6b69-488c-b951-160495ac6a32" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_8089d5bb-9107-4734-b07b-8868a75bdbe2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_f2cf1127-6b69-488c-b951-160495ac6a32" xlink:to="loc_us-gaap_OperatingSegmentsMember_8089d5bb-9107-4734-b07b-8868a75bdbe2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_16266436-dc5a-4e71-a0f5-167fa14a1e85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_f2cf1127-6b69-488c-b951-160495ac6a32" xlink:to="loc_us-gaap_CorporateNonSegmentMember_16266436-dc5a-4e71-a0f5-167fa14a1e85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_df0ea0b3-428e-44d4-bfbf-a560b73eaeb4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_Revenues_df0ea0b3-428e-44d4-bfbf-a560b73eaeb4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PremiumsEarnedNet_3afd8781-78d1-49ed-ad51-adefe77d5143" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PremiumsEarnedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_PremiumsEarnedNet_3afd8781-78d1-49ed-ad51-adefe77d5143" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncome_96af201c-5588-4f45-8c4f-a99d7262f6c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_OtherIncome_96af201c-5588-4f45-8c4f-a99d7262f6c2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BenefitsLossesAndExpenses_38b73b2e-dbb7-4568-a898-98ee19a59849" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BenefitsLossesAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_BenefitsLossesAndExpenses_38b73b2e-dbb7-4568-a898-98ee19a59849" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_f21ac3a5-4096-4ab7-ae93-9f9bc2ddbbe6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PolicyholderBenefitsAndClaimsIncurredNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_PolicyholderBenefitsAndClaimsIncurredNet_f21ac3a5-4096-4ab7-ae93-9f9bc2ddbbe6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_UnderwritingAcquisitionAndInsuranceExpenses_73add90c-401c-4820-a93c-a29fa81e5ec2" xlink:href="cinf-20250930.xsd#cinf_UnderwritingAcquisitionAndInsuranceExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_cinf_UnderwritingAcquisitionAndInsuranceExpenses_73add90c-401c-4820-a93c-a29fa81e5ec2" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherExpenses_9dee06e1-a0a2-4a2d-b3e8-91c583e7487a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_OtherExpenses_9dee06e1-a0a2-4a2d-b3e8-91c583e7487a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_18df9e1d-e278-443f-9bef-2e35945ff6cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_4f2bf90a-ab31-4d7c-b51c-1e665a43250e" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_18df9e1d-e278-443f-9bef-2e35945ff6cc" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.cinfin.com/role/SegmentInformationReconciliationofAssetsfromsegmentstoConsolidatedDetails" xlink:type="simple" xlink:href="cinf-20250930.xsd#SegmentInformationReconciliationofAssetsfromsegmentstoConsolidatedDetails"/>
  <link:definitionLink xlink:role="http://www.cinfin.com/role/SegmentInformationReconciliationofAssetsfromsegmentstoConsolidatedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_80d7e8fb-b883-4615-96db-99d3a7211cf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_3c937056-0ec6-41c9-b249-7d0de7aa3a33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_80d7e8fb-b883-4615-96db-99d3a7211cf6" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_3c937056-0ec6-41c9-b249-7d0de7aa3a33" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_3c937056-0ec6-41c9-b249-7d0de7aa3a33" xlink:to="loc_srt_ConsolidationItemsAxis_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d" xlink:to="loc_srt_ConsolidationItemsDomain_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_005fd999-21cb-4f9f-902c-279a62ac5fa7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_baac4622-7c1d-4b0c-ae9a-3bb9fe41fc0d" xlink:to="loc_srt_ConsolidationItemsDomain_005fd999-21cb-4f9f-902c-279a62ac5fa7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_5e103d76-925b-4589-a529-0671f26e74f9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_005fd999-21cb-4f9f-902c-279a62ac5fa7" xlink:to="loc_us-gaap_OperatingSegmentsMember_5e103d76-925b-4589-a529-0671f26e74f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_6d0f278b-ddcb-4d91-8d88-c274fa9844de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_005fd999-21cb-4f9f-902c-279a62ac5fa7" xlink:to="loc_us-gaap_CorporateNonSegmentMember_6d0f278b-ddcb-4d91-8d88-c274fa9844de" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_e0d12d7e-75eb-4c9b-94ac-213f22df000a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_3c937056-0ec6-41c9-b249-7d0de7aa3a33" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_e0d12d7e-75eb-4c9b-94ac-213f22df000a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e0d12d7e-75eb-4c9b-94ac-213f22df000a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e0d12d7e-75eb-4c9b-94ac-213f22df000a" xlink:to="loc_us-gaap_SegmentDomain_e0d12d7e-75eb-4c9b-94ac-213f22df000a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_99c3f68f-a375-4810-81b4-bcc2696720c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_e0d12d7e-75eb-4c9b-94ac-213f22df000a" xlink:to="loc_us-gaap_SegmentDomain_99c3f68f-a375-4810-81b4-bcc2696720c6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_LifeInsuranceMember_32461f9b-5291-4257-8877-62c28d17bc1c" xlink:href="cinf-20250930.xsd#cinf_LifeInsuranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_99c3f68f-a375-4810-81b4-bcc2696720c6" xlink:to="loc_cinf_LifeInsuranceMember_32461f9b-5291-4257-8877-62c28d17bc1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_cinf_InvestmentSegmentOfCINFMember_e6750e84-e6ef-416c-9eb5-3d325b44ea48" xlink:href="cinf-20250930.xsd#cinf_InvestmentSegmentOfCINFMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_99c3f68f-a375-4810-81b4-bcc2696720c6" xlink:to="loc_cinf_InvestmentSegmentOfCINFMember_e6750e84-e6ef-416c-9eb5-3d325b44ea48" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_6f63a35b-722f-4781-9ecf-42c2c08fdcbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_80d7e8fb-b883-4615-96db-99d3a7211cf6" xlink:to="loc_us-gaap_Assets_6f63a35b-722f-4781-9ecf-42c2c08fdcbe" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
