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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2024 Workiva-->
<!--r:3950f1bc-760f-4a16-af00-00f62a26bc27,g:79d25d3b-b427-4e90-b1c5-8f2bd19e04ef-->
<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.inotivco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="simple" xlink:href="notv-20240331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFOPERATIONS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_55c98149-4ca3-45b2-a039-b3914057140e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_StatementTable_55c98149-4ca3-45b2-a039-b3914057140e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_5fe604de-12aa-40a6-9598-a68395b1277a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_55c98149-4ca3-45b2-a039-b3914057140e" xlink:to="loc_srt_ProductOrServiceAxis_5fe604de-12aa-40a6-9598-a68395b1277a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5fe604de-12aa-40a6-9598-a68395b1277a_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_5fe604de-12aa-40a6-9598-a68395b1277a" xlink:to="loc_srt_ProductsAndServicesDomain_5fe604de-12aa-40a6-9598-a68395b1277a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_5b4c329e-6e31-411b-8004-8e099f115e26" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_5fe604de-12aa-40a6-9598-a68395b1277a" xlink:to="loc_srt_ProductsAndServicesDomain_5b4c329e-6e31-411b-8004-8e099f115e26" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_bd1e2df3-c98d-4468-8bac-c441d38f0d66" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5b4c329e-6e31-411b-8004-8e099f115e26" xlink:to="loc_us-gaap_ServiceMember_bd1e2df3-c98d-4468-8bac-c441d38f0d66" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_4dc39343-5036-4948-9391-2c274398b329" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_5b4c329e-6e31-411b-8004-8e099f115e26" xlink:to="loc_us-gaap_ProductMember_4dc39343-5036-4948-9391-2c274398b329" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5e22bc73-9be2-4f30-9b40-9be06b5fcf65" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_5e22bc73-9be2-4f30-9b40-9be06b5fcf65" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_71bd0a0a-19f0-4c51-87ba-56860b4012a7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization_71bd0a0a-19f0-4c51-87ba-56860b4012a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingExpense_5496b01c-2a73-4d50-a299-bfda99e7c183" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SellingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_SellingExpense_5496b01c-2a73-4d50-a299-bfda99e7c183" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_f97d0265-b02b-412f-a0db-03755224037e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_f97d0265-b02b-412f-a0db-03755224037e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_a863de14-c52b-48dc-882a-985a5cca4b17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_a863de14-c52b-48dc-882a-985a5cca4b17" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCostAndExpenseOperating_8e2e110c-15e0-477a-bec1-f60038dfbc9c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherCostAndExpenseOperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_OtherCostAndExpenseOperating_8e2e110c-15e0-477a-bec1-f60038dfbc9c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_46471e10-4a9d-4fe3-8671-40a992eb5105" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_dc88d100-6b04-4779-b33c-e9c4554ccd3e" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_46471e10-4a9d-4fe3-8671-40a992eb5105" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_c710e054-a8ae-43bb-80ca-4705530652ba" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_OperatingIncomeLoss_c710e054-a8ae-43bb-80ca-4705530652ba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncomeAndExpensesAbstract_2710040f-0b26-4069-81b1-53f003cd984d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIncomeAndExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_OtherIncomeAndExpensesAbstract_2710040f-0b26-4069-81b1-53f003cd984d" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_ec8276db-0d85-424e-a79b-04141a6417b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_2710040f-0b26-4069-81b1-53f003cd984d" xlink:to="loc_us-gaap_InterestExpense_ec8276db-0d85-424e-a79b-04141a6417b8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_29ad9bc3-327c-4403-a22d-fb66c151f2d8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherIncomeAndExpensesAbstract_2710040f-0b26-4069-81b1-53f003cd984d" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_29ad9bc3-327c-4403-a22d-fb66c151f2d8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_76d33e0c-fa0b-4824-be2b-270b706293a0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_76d33e0c-fa0b-4824-be2b-270b706293a0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_972022ec-efe1-41c8-ac57-dccaf7aa0153" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_972022ec-efe1-41c8-ac57-dccaf7aa0153" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_43e34563-055f-47d5-8702-ced42337173c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest_43e34563-055f-47d5-8702-ced42337173c" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_2bc2af86-ef4a-4622-bda6-d5d11d6905e8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLossAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_NetIncomeLossAttributableToNoncontrollingInterest_2bc2af86-ef4a-4622-bda6-d5d11d6905e8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_6869f980-4df7-42de-a592-56242b663c78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_NetIncomeLoss_6869f980-4df7-42de-a592-56242b663c78" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_20848889-85ad-4dec-bcbd-b255299cf23f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_EarningsPerShareAbstract_20848889-85ad-4dec-bcbd-b255299cf23f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_8141742f-5b29-470f-9321-46f894e7ff64" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_20848889-85ad-4dec-bcbd-b255299cf23f" xlink:to="loc_us-gaap_EarningsPerShareBasic_8141742f-5b29-470f-9321-46f894e7ff64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_c42b3894-02aa-4353-b1b2-ae41972ce806" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_20848889-85ad-4dec-bcbd-b255299cf23f" xlink:to="loc_us-gaap_EarningsPerShareDiluted_c42b3894-02aa-4353-b1b2-ae41972ce806" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_773f5bc0-61fa-4c42-bbb7-da8139754226" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_c1f6f1ea-b698-4e4f-8a37-6e7a85f7e5bb" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_773f5bc0-61fa-4c42-bbb7-da8139754226" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_4d4c6316-59c3-47b3-b3e9-7fcbcb3d2047" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_773f5bc0-61fa-4c42-bbb7-da8139754226" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_4d4c6316-59c3-47b3-b3e9-7fcbcb3d2047" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_87f946f9-5706-49a6-b181-4a0ee51b2f77" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingAbstract_773f5bc0-61fa-4c42-bbb7-da8139754226" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_87f946f9-5706-49a6-b181-4a0ee51b2f77" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYANDNONCONTROLLINGINTEREST" xlink:type="simple" xlink:href="notv-20240331.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYANDNONCONTROLLINGINTEREST"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYANDNONCONTROLLINGINTEREST" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_8c99aaa7-180a-45a6-9523-5c83aec42a67" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_98941523-7826-4389-8e12-bdf5f9a0075a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_8c99aaa7-180a-45a6-9523-5c83aec42a67" xlink:to="loc_us-gaap_StatementTable_98941523-7826-4389-8e12-bdf5f9a0075a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_2b05f36f-a55c-43fa-947e-da0388a4d516" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_98941523-7826-4389-8e12-bdf5f9a0075a" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_2b05f36f-a55c-43fa-947e-da0388a4d516" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_2b05f36f-a55c-43fa-947e-da0388a4d516_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2b05f36f-a55c-43fa-947e-da0388a4d516" xlink:to="loc_us-gaap_EquityComponentDomain_2b05f36f-a55c-43fa-947e-da0388a4d516_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_2b05f36f-a55c-43fa-947e-da0388a4d516" xlink:to="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_f9293919-1447-49f4-8c45-0c9c366d4982" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:to="loc_us-gaap_CommonStockMember_f9293919-1447-49f4-8c45-0c9c366d4982" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_bc70f55a-9a3f-4400-9a8b-83dd82b5156c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_bc70f55a-9a3f-4400-9a8b-83dd82b5156c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_0cfb3d6d-d162-4ca2-a699-01f954f1a9ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:to="loc_us-gaap_RetainedEarningsMember_0cfb3d6d-d162-4ca2-a699-01f954f1a9ec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9e2234b5-5381-473c-93d8-6da5cd11c5b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_9e2234b5-5381-473c-93d8-6da5cd11c5b5" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncontrollingInterestMember_86ebf786-9804-48e4-9905-03810f3f97e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncontrollingInterestMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_edf29d82-3c68-4a84-a6f3-98e9e5a7e0c9" xlink:to="loc_us-gaap_NoncontrollingInterestMember_86ebf786-9804-48e4-9905-03810f3f97e6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_8c99aaa7-180a-45a6-9523-5c83aec42a67" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_5f7303f4-07b5-4758-b4cc-82a6213b06df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_5f7303f4-07b5-4758-b4cc-82a6213b06df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_1d7d5206-1b51-477c-928b-da8aac2afcc5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_1d7d5206-1b51-477c-928b-da8aac2afcc5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_a89faba0-0d4d-40f0-a3f2-a30ea1ee13c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_NetIncomeLoss_a89faba0-0d4d-40f0-a3f2-a30ea1ee13c0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_081473f4-4a69-4c05-bcad-8812f5fde170" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders_081473f4-4a69-4c05-bcad-8812f5fde170" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_d6802674-45eb-43cc-9fca-ccf40d79ecbb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans_d6802674-45eb-43cc-9fca-ccf40d79ecbb" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_e0475378-4f91-4e0e-9a58-116ca03c5892" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeStockPurchasePlan_e0475378-4f91-4e0e-9a58-116ca03c5892" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_612e3e4e-6358-407d-8687-9018cf61da16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_612e3e4e-6358-407d-8687-9018cf61da16" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax_1e9ca237-c9f7-41b3-b363-ec2020e7fdfb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax_1e9ca237-c9f7-41b3-b363-ec2020e7fdfb" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_3440cca5-13d6-41aa-8c8b-5c6fe4813c21" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossForeignCurrencyTransactionAndTranslationAdjustmentNetOfTax_3440cca5-13d6-41aa-8c8b-5c6fe4813c21" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityOther_ebb56fca-a11f-4072-ab47-adc9fee61eef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_8b1c26d8-df65-41f5-aae3-b94a4de9a9ee" xlink:to="loc_us-gaap_StockholdersEquityOther_ebb56fca-a11f-4072-ab47-adc9fee61eef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_2b86cddc-5403-46b3-b672-423de3a1e76b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest_884129c3-b09d-4423-9547-c3243984dcdf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/DESCRIPTIONOFTHEBUSINESSANDBASISOFPRESENTATIONNarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#DESCRIPTIONOFTHEBUSINESSANDBASISOFPRESENTATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/DESCRIPTIONOFTHEBUSINESSANDBASISOFPRESENTATIONNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_2f1b9081-0832-4a19-b1df-3559c5facde6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_2f1b9081-0832-4a19-b1df-3559c5facde6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_2f1b9081-0832-4a19-b1df-3559c5facde6_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2f1b9081-0832-4a19-b1df-3559c5facde6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_2f1b9081-0832-4a19-b1df-3559c5facde6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_27e6d0b7-2494-433e-b5c3-07d65cf26a12" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_2f1b9081-0832-4a19-b1df-3559c5facde6" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_27e6d0b7-2494-433e-b5c3-07d65cf26a12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_7daf27c2-3f64-4f71-b1e6-80da84d75903" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_27e6d0b7-2494-433e-b5c3-07d65cf26a12" xlink:to="loc_us-gaap_SubsequentEventMember_7daf27c2-3f64-4f71-b1e6-80da84d75903" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_ddfbf5dc-50bc-46b7-b821-c7a350c249be" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_CreditFacilityAxis_ddfbf5dc-50bc-46b7-b821-c7a350c249be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_ddfbf5dc-50bc-46b7-b821-c7a350c249be_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_ddfbf5dc-50bc-46b7-b821-c7a350c249be" xlink:to="loc_us-gaap_CreditFacilityDomain_ddfbf5dc-50bc-46b7-b821-c7a350c249be_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_8625c62c-98a6-4ea0-bdf6-9a71426db3c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_ddfbf5dc-50bc-46b7-b821-c7a350c249be" xlink:to="loc_us-gaap_CreditFacilityDomain_8625c62c-98a6-4ea0-bdf6-9a71426db3c1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_22e71f24-7488-4aac-9fb5-f2ec8c8464af" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_8625c62c-98a6-4ea0-bdf6-9a71426db3c1" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_22e71f24-7488-4aac-9fb5-f2ec8c8464af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_001ddba5-8a5d-4db0-aabd-25694168c6d1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_srt_MajorCustomersAxis_001ddba5-8a5d-4db0-aabd-25694168c6d1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_001ddba5-8a5d-4db0-aabd-25694168c6d1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_001ddba5-8a5d-4db0-aabd-25694168c6d1" xlink:to="loc_srt_NameOfMajorCustomerDomain_001ddba5-8a5d-4db0-aabd-25694168c6d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_022fd27d-a4f6-4c8c-8a96-e4154016d724" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_001ddba5-8a5d-4db0-aabd-25694168c6d1" xlink:to="loc_srt_NameOfMajorCustomerDomain_022fd27d-a4f6-4c8c-8a96-e4154016d724" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_CambodianNhpVendorMember_4db391f3-d4e8-4132-84a3-ee9b5bb7b9d5" xlink:href="notv-20240331.xsd#notv_CambodianNhpVendorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_022fd27d-a4f6-4c8c-8a96-e4154016d724" xlink:to="loc_notv_CambodianNhpVendorMember_4db391f3-d4e8-4132-84a3-ee9b5bb7b9d5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_OneCustomerMember_dc6ad3f4-23f0-444f-ba36-97d2bb8a30fc" xlink:href="notv-20240331.xsd#notv_OneCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_022fd27d-a4f6-4c8c-8a96-e4154016d724" xlink:to="loc_notv_OneCustomerMember_dc6ad3f4-23f0-444f-ba36-97d2bb8a30fc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7afaabdf-376b-4eeb-98c3-5e592c2ab98d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7afaabdf-376b-4eeb-98c3-5e592c2ab98d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_7afaabdf-376b-4eeb-98c3-5e592c2ab98d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7afaabdf-376b-4eeb-98c3-5e592c2ab98d" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_7afaabdf-376b-4eeb-98c3-5e592c2ab98d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a0bc8f1d-17c0-4f40-8e2d-e95b89282ebb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_7afaabdf-376b-4eeb-98c3-5e592c2ab98d" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a0bc8f1d-17c0-4f40-8e2d-e95b89282ebb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerMember_f8d957b4-dc35-4332-b4b3-d023912da173" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a0bc8f1d-17c0-4f40-8e2d-e95b89282ebb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerMember_f8d957b4-dc35-4332-b4b3-d023912da173" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsTotalMember_4beb33e9-cd08-4952-9e3a-e0a90ff59c04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CostOfGoodsTotalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_a0bc8f1d-17c0-4f40-8e2d-e95b89282ebb" xlink:to="loc_us-gaap_CostOfGoodsTotalMember_4beb33e9-cd08-4952-9e3a-e0a90ff59c04" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_7c1164e0-0a44-4b5a-944a-bddd5d714418" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_7c1164e0-0a44-4b5a-944a-bddd5d714418" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_7c1164e0-0a44-4b5a-944a-bddd5d714418_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_7c1164e0-0a44-4b5a-944a-bddd5d714418" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_7c1164e0-0a44-4b5a-944a-bddd5d714418_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_33f19d66-3a44-4110-b003-14663614c98a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_7c1164e0-0a44-4b5a-944a-bddd5d714418" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_33f19d66-3a44-4110-b003-14663614c98a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_81a287b1-d100-461c-83d3-4bd37ef1c922" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_33f19d66-3a44-4110-b003-14663614c98a" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_81a287b1-d100-461c-83d3-4bd37ef1c922" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SupplierConcentrationRiskMember_ab05fbe4-f196-4d63-840a-62b063f9a212" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SupplierConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_33f19d66-3a44-4110-b003-14663614c98a" xlink:to="loc_us-gaap_SupplierConcentrationRiskMember_ab05fbe4-f196-4d63-840a-62b063f9a212" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_d93caa5c-f281-44c3-8c8c-66f8b96c7cec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_d93caa5c-f281-44c3-8c8c-66f8b96c7cec" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_d93caa5c-f281-44c3-8c8c-66f8b96c7cec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_d93caa5c-f281-44c3-8c8c-66f8b96c7cec" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_d93caa5c-f281-44c3-8c8c-66f8b96c7cec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_fecfc79d-92eb-4de6-9172-a6cf28f1cff6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionBySupplierAxis_d93caa5c-f281-44c3-8c8c-66f8b96c7cec" xlink:to="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_fecfc79d-92eb-4de6-9172-a6cf28f1cff6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_OneVendorMember_2ba36e4a-f668-49d8-8e55-1e6d3e80193f" xlink:href="notv-20240331.xsd#notv_OneVendorMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedGoodsAndNonemployeeServicesTransactionSupplierDomain_fecfc79d-92eb-4de6-9172-a6cf28f1cff6" xlink:to="loc_notv_OneVendorMember_2ba36e4a-f668-49d8-8e55-1e6d3e80193f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_216303af-0687-4f7e-a9f1-110694b23e25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_DebtInstrumentAxis_216303af-0687-4f7e-a9f1-110694b23e25" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_216303af-0687-4f7e-a9f1-110694b23e25_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_216303af-0687-4f7e-a9f1-110694b23e25" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_216303af-0687-4f7e-a9f1-110694b23e25_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_03778e11-6d40-4a30-8236-2941a0f3e51f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_216303af-0687-4f7e-a9f1-110694b23e25" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_03778e11-6d40-4a30-8236-2941a0f3e51f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ConvertibleSeniorNotesDue2027Member_117f34c1-9a8e-4dfe-ae2c-64a949a32971" xlink:href="notv-20240331.xsd#notv_ConvertibleSeniorNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_03778e11-6d40-4a30-8236-2941a0f3e51f" xlink:to="loc_notv_ConvertibleSeniorNotesDue2027Member_117f34c1-9a8e-4dfe-ae2c-64a949a32971" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_31c269e0-7ce0-401d-84be-0f21c813c4b8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_31c269e0-7ce0-401d-84be-0f21c813c4b8" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_31c269e0-7ce0-401d-84be-0f21c813c4b8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_31c269e0-7ce0-401d-84be-0f21c813c4b8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_31c269e0-7ce0-401d-84be-0f21c813c4b8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_d3db5454-3d4f-42c6-add3-6224626e2913" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_31c269e0-7ce0-401d-84be-0f21c813c4b8" xlink:to="loc_us-gaap_LossContingencyNatureDomain_d3db5454-3d4f-42c6-add3-6224626e2913" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_USDOJAgreementInPrincipleMember_20e65ded-70f7-495c-9e3e-a706d265aa48" xlink:href="notv-20240331.xsd#notv_USDOJAgreementInPrincipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_d3db5454-3d4f-42c6-add3-6224626e2913" xlink:to="loc_notv_USDOJAgreementInPrincipleMember_20e65ded-70f7-495c-9e3e-a706d265aa48" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementScenarioAxis_a0d14112-abe6-4c82-b4a8-e07c346f195f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_srt_StatementScenarioAxis_a0d14112-abe6-4c82-b4a8-e07c346f195f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_a0d14112-abe6-4c82-b4a8-e07c346f195f_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementScenarioAxis_a0d14112-abe6-4c82-b4a8-e07c346f195f" xlink:to="loc_srt_ScenarioUnspecifiedDomain_a0d14112-abe6-4c82-b4a8-e07c346f195f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioUnspecifiedDomain_d41db663-7ad1-42bf-add6-305a0379a1e8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioUnspecifiedDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementScenarioAxis_a0d14112-abe6-4c82-b4a8-e07c346f195f" xlink:to="loc_srt_ScenarioUnspecifiedDomain_d41db663-7ad1-42bf-add6-305a0379a1e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ScenarioForecastMember_c8a076ca-40ca-45b5-8e3c-c1be6908d857" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ScenarioForecastMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ScenarioUnspecifiedDomain_d41db663-7ad1-42bf-add6-305a0379a1e8" xlink:to="loc_srt_ScenarioForecastMember_c8a076ca-40ca-45b5-8e3c-c1be6908d857" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_be5d7e76-7d3b-453c-9094-97df1c30116b" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_srt_RangeAxis_be5d7e76-7d3b-453c-9094-97df1c30116b" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_be5d7e76-7d3b-453c-9094-97df1c30116b_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_be5d7e76-7d3b-453c-9094-97df1c30116b" xlink:to="loc_srt_RangeMember_be5d7e76-7d3b-453c-9094-97df1c30116b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_af927b31-ee7b-4509-99b0-96a289f4ce6f" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_be5d7e76-7d3b-453c-9094-97df1c30116b" xlink:to="loc_srt_RangeMember_af927b31-ee7b-4509-99b0-96a289f4ce6f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_8875e391-cc20-46c7-bdaa-2ac1dd162673" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_af927b31-ee7b-4509-99b0-96a289f4ce6f" xlink:to="loc_srt_MinimumMember_8875e391-cc20-46c7-bdaa-2ac1dd162673" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_d9501152-ebbc-4d85-b6dd-a328d0a759d5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_af927b31-ee7b-4509-99b0-96a289f4ce6f" xlink:to="loc_srt_MaximumMember_d9501152-ebbc-4d85-b6dd-a328d0a759d5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_srt_StatementGeographicalAxis_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a" xlink:to="loc_srt_SegmentGeographicalDomain_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_c1b02c69-9554-47ab-be56-887da4817505" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_3fc5d6f0-7bf3-4a52-86fc-2a1f29a4eb8a" xlink:to="loc_srt_SegmentGeographicalDomain_c1b02c69-9554-47ab-be56-887da4817505" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_KH_62c89fe5-46a0-409e-99ec-11cdb197f897" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_KH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_c1b02c69-9554-47ab-be56-887da4817505" xlink:to="loc_country_KH_62c89fe5-46a0-409e-99ec-11cdb197f897" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_f9165773-23a8-45d1-ba6e-28df84748e3c" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_e3417942-e835-455b-a0d8-fc883eeec11d" xlink:to="loc_srt_ProductOrServiceAxis_f9165773-23a8-45d1-ba6e-28df84748e3c" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_f9165773-23a8-45d1-ba6e-28df84748e3c_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_f9165773-23a8-45d1-ba6e-28df84748e3c" xlink:to="loc_srt_ProductsAndServicesDomain_f9165773-23a8-45d1-ba6e-28df84748e3c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_6e48bd39-8c9b-4678-91f0-18d9ec0778b9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_f9165773-23a8-45d1-ba6e-28df84748e3c" xlink:to="loc_srt_ProductsAndServicesDomain_6e48bd39-8c9b-4678-91f0-18d9ec0778b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_994e5d7d-25e8-483e-82a4-ca9c2e68dafd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_6e48bd39-8c9b-4678-91f0-18d9ec0778b9" xlink:to="loc_us-gaap_ProductMember_994e5d7d-25e8-483e-82a4-ca9c2e68dafd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_15a68617-80a1-440c-aeaf-79904ef249b0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_NumberOfReportableSegments_15a68617-80a1-440c-aeaf-79904ef249b0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_6fdb0006-bc88-40b0-bbb3-d93fc0230462" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_6fdb0006-bc88-40b0-bbb3-d93fc0230462" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyLossInPeriod_a8470be5-166e-4c43-92bd-2b646d57d5e6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyLossInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LossContingencyLossInPeriod_a8470be5-166e-4c43-92bd-2b646d57d5e6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_64580ccb-e1b5-408a-a9aa-a7fea046f228" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualCarryingValueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueCurrent_64580ccb-e1b5-408a-a9aa-a7fea046f228" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_9321019f-7e48-4292-b4b0-dd24818b2c5d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualCarryingValueNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LossContingencyAccrualCarryingValueNoncurrent_9321019f-7e48-4292-b4b0-dd24818b2c5d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_e8179ed9-a12d-4686-b2ac-2cc1e20d48a9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_e8179ed9-a12d-4686-b2ac-2cc1e20d48a9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyEstimatedLossPeriod_b5e6f968-51a6-4236-935f-17e22b2ff084" xlink:href="notv-20240331.xsd#notv_LossContingencyEstimatedLossPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_LossContingencyEstimatedLossPeriod_b5e6f968-51a6-4236-935f-17e22b2ff084" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfGovernmentOfficialsIncluded_df1dffd5-cc1b-49a9-8144-fb950e33ea26" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfGovernmentOfficialsIncluded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_LossContingencyNumberOfGovernmentOfficialsIncluded_df1dffd5-cc1b-49a9-8144-fb950e33ea26" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfImports_92465cd5-9f6d-4de8-80f2-4e48168acef0" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfImports"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_LossContingencyNumberOfImports_92465cd5-9f6d-4de8-80f2-4e48168acef0" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfSubsidiaries_a68572f4-4f35-4b12-be86-eec99a0394e1" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfSubsidiaries"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_LossContingencyNumberOfSubsidiaries_a68572f4-4f35-4b12-be86-eec99a0394e1" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice_e151120c-42b1-429f-8e05-b49eb921e240" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityCumulativeCatchUpAdjustmentToRevenueChangeInEstimateOfTransactionPrice_e151120c-42b1-429f-8e05-b49eb921e240" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0aaeaadd-e25a-421e-8877-c8b953731192" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_0aaeaadd-e25a-421e-8877-c8b953731192" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f12ae3e6-738c-4e6c-998b-6e0c25351cbf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CashAndCashEquivalentsAtCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_CashAndCashEquivalentsAtCarryingValue_f12ae3e6-738c-4e6c-998b-6e0c25351cbf" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCredit_8bcdbdc0-eeaa-49e8-bfaf-a2632827ba32" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LineOfCredit_8bcdbdc0-eeaa-49e8-bfaf-a2632827ba32" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantChargesAddBackAllowance_cdd1f5cd-0181-455d-a5cc-9c9f2d766e60" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantChargesAddBackAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_DebtInstrumentCovenantChargesAddBackAllowance_cdd1f5cd-0181-455d-a5cc-9c9f2d766e60" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantDefaultThresholdPeriodAfterNotification_2acea49d-81ba-4bdf-b914-680b03166256" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantDefaultThresholdPeriodAfterNotification"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_DebtInstrumentCovenantDefaultThresholdPeriodAfterNotification_2acea49d-81ba-4bdf-b914-680b03166256" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantPercentageHeldByTrusteesOrHoldersThatCanEffectDefaultAcceleration_80f5d5be-cc2b-48d1-8a54-2eaa423cb34b" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantPercentageHeldByTrusteesOrHoldersThatCanEffectDefaultAcceleration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_DebtInstrumentCovenantPercentageHeldByTrusteesOrHoldersThatCanEffectDefaultAcceleration_80f5d5be-cc2b-48d1-8a54-2eaa423cb34b" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantDurationFollowingFiscalQuarterWithinWhichADefaultCanBeCured_126cebc0-17d1-49f1-9b4b-8c3fb5daef11" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantDurationFollowingFiscalQuarterWithinWhichADefaultCanBeCured"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_DebtInstrumentCovenantDurationFollowingFiscalQuarterWithinWhichADefaultCanBeCured_126cebc0-17d1-49f1-9b4b-8c3fb5daef11" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantDurationFollowingFiscalYeaEndWithinWhichADefaultCanBeCured_c5002e19-24cc-46ff-b7d1-26752c39a96c" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantDurationFollowingFiscalYeaEndWithinWhichADefaultCanBeCured"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_notv_DebtInstrumentCovenantDurationFollowingFiscalYeaEndWithinWhichADefaultCanBeCured_c5002e19-24cc-46ff-b7d1-26752c39a96c" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_e7e82410-05b3-4171-9068-977956f2bdf4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_e7e82410-05b3-4171-9068-977956f2bdf4" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_43b97660-f426-4285-81d5-4eea842a6ce1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_264bd155-8775-48b1-91fc-b21856ab6deb" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_43b97660-f426-4285-81d5-4eea842a6ce1" xlink:type="arc" order="20"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONNarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#SEGMENTANDGEOGRAPHICINFORMATIONNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_ea0fd1d5-5e77-4d37-a3bd-44df195ca6c4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_bd6cf462-646a-4405-bbfa-63430cab1bae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ea0fd1d5-5e77-4d37-a3bd-44df195ca6c4" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_bd6cf462-646a-4405-bbfa-63430cab1bae" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_77ea294e-4b35-4309-aecf-0e7119298edc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_bd6cf462-646a-4405-bbfa-63430cab1bae" xlink:to="loc_srt_ConsolidationItemsAxis_77ea294e-4b35-4309-aecf-0e7119298edc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_77ea294e-4b35-4309-aecf-0e7119298edc_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_77ea294e-4b35-4309-aecf-0e7119298edc" xlink:to="loc_srt_ConsolidationItemsDomain_77ea294e-4b35-4309-aecf-0e7119298edc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_3f79eb40-64e7-445c-b3f1-67fa85ff41d2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_77ea294e-4b35-4309-aecf-0e7119298edc" xlink:to="loc_srt_ConsolidationItemsDomain_3f79eb40-64e7-445c-b3f1-67fa85ff41d2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_93c6cdb4-1370-4483-8f9f-f0b790a92800" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_3f79eb40-64e7-445c-b3f1-67fa85ff41d2" xlink:to="loc_us-gaap_IntersegmentEliminationMember_93c6cdb4-1370-4483-8f9f-f0b790a92800" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_32849086-b127-4757-af5c-ecd032b66ab3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_ea0fd1d5-5e77-4d37-a3bd-44df195ca6c4" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_32849086-b127-4757-af5c-ecd032b66ab3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONOperatingSegmentsRevenueandOperatingIncomeLossDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#SEGMENTANDGEOGRAPHICINFORMATIONOperatingSegmentsRevenueandOperatingIncomeLossDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONOperatingSegmentsRevenueandOperatingIncomeLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6de46fe-c55c-43b3-b78f-2b92412233b7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6de46fe-c55c-43b3-b78f-2b92412233b7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_77c39846-b1d0-48d7-b59f-8bec6b5c9133" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6de46fe-c55c-43b3-b78f-2b92412233b7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_77c39846-b1d0-48d7-b59f-8bec6b5c9133" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_77c39846-b1d0-48d7-b59f-8bec6b5c9133_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_77c39846-b1d0-48d7-b59f-8bec6b5c9133" xlink:to="loc_us-gaap_SegmentDomain_77c39846-b1d0-48d7-b59f-8bec6b5c9133_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_e558d167-2987-4120-bb85-13ec7ca94898" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_77c39846-b1d0-48d7-b59f-8bec6b5c9133" xlink:to="loc_us-gaap_SegmentDomain_e558d167-2987-4120-bb85-13ec7ca94898" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DiscoveryAndSafetyAssessmentSegmentMember_26eb2b8c-4a48-4d83-8cec-fc40bde92f9f" xlink:href="notv-20240331.xsd#notv_DiscoveryAndSafetyAssessmentSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e558d167-2987-4120-bb85-13ec7ca94898" xlink:to="loc_notv_DiscoveryAndSafetyAssessmentSegmentMember_26eb2b8c-4a48-4d83-8cec-fc40bde92f9f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ResearchModelsAndServicesSegmentMember_9a07e9bf-a135-4646-80ea-afbc65b77b18" xlink:href="notv-20240331.xsd#notv_ResearchModelsAndServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_e558d167-2987-4120-bb85-13ec7ca94898" xlink:to="loc_notv_ResearchModelsAndServicesSegmentMember_9a07e9bf-a135-4646-80ea-afbc65b77b18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_4d7d1272-dd30-4821-a9ad-596387a690f1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6de46fe-c55c-43b3-b78f-2b92412233b7" xlink:to="loc_srt_ProductOrServiceAxis_4d7d1272-dd30-4821-a9ad-596387a690f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_4d7d1272-dd30-4821-a9ad-596387a690f1_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_4d7d1272-dd30-4821-a9ad-596387a690f1" xlink:to="loc_srt_ProductsAndServicesDomain_4d7d1272-dd30-4821-a9ad-596387a690f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_e7f62061-8bcb-4ef5-bd17-c43c842aecfb" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_4d7d1272-dd30-4821-a9ad-596387a690f1" xlink:to="loc_srt_ProductsAndServicesDomain_e7f62061-8bcb-4ef5-bd17-c43c842aecfb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_2dc3c773-3d5f-4951-b237-4ed634782f50" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e7f62061-8bcb-4ef5-bd17-c43c842aecfb" xlink:to="loc_us-gaap_ServiceMember_2dc3c773-3d5f-4951-b237-4ed634782f50" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_64fed762-e21d-428a-a319-550ad5c05bec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_e7f62061-8bcb-4ef5-bd17-c43c842aecfb" xlink:to="loc_us-gaap_ProductMember_64fed762-e21d-428a-a319-550ad5c05bec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_f6b82514-1a43-4782-acad-713aa7110d47" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_b6de46fe-c55c-43b3-b78f-2b92412233b7" xlink:to="loc_srt_ConsolidationItemsAxis_f6b82514-1a43-4782-acad-713aa7110d47" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_f6b82514-1a43-4782-acad-713aa7110d47_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_f6b82514-1a43-4782-acad-713aa7110d47" xlink:to="loc_srt_ConsolidationItemsDomain_f6b82514-1a43-4782-acad-713aa7110d47_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_c00230c2-b8e2-41ba-b16d-3038821cb0a6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_f6b82514-1a43-4782-acad-713aa7110d47" xlink:to="loc_srt_ConsolidationItemsDomain_c00230c2-b8e2-41ba-b16d-3038821cb0a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_e0201bc2-1cb0-4b21-bca0-11f242575f93" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_c00230c2-b8e2-41ba-b16d-3038821cb0a6" xlink:to="loc_us-gaap_OperatingSegmentsMember_e0201bc2-1cb0-4b21-bca0-11f242575f93" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_f93120c3-cc32-4d71-ba0f-86907f7f6475" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_c00230c2-b8e2-41ba-b16d-3038821cb0a6" xlink:to="loc_us-gaap_CorporateNonSegmentMember_f93120c3-cc32-4d71-ba0f-86907f7f6475" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cc9bc4b2-6e9f-40e3-828b-73a7913a7885" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_cc9bc4b2-6e9f-40e3-828b-73a7913a7885" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_9ee9a0dc-72e2-4eee-9066-9f6be26b51ab" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_OperatingIncomeLoss_9ee9a0dc-72e2-4eee-9066-9f6be26b51ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_d34d959d-32cd-428c-a3a6-cc2951ba4b55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_InterestExpense_d34d959d-32cd-428c-a3a6-cc2951ba4b55" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_cd101059-aa84-48d0-b3a4-cedcca802f9b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_cd101059-aa84-48d0-b3a4-cedcca802f9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d6026150-d239-4db0-a0fd-9598c0d55816" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_d6026150-d239-4db0-a0fd-9598c0d55816" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationAndAmortization_94b04d91-45fe-4307-b1b9-3a4dd63cf457" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_DepreciationAndAmortization_94b04d91-45fe-4307-b1b9-3a4dd63cf457" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireProductiveAssets_dd0c43b5-816b-4146-a288-49fdc9e30317" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireProductiveAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_9918ab69-5b40-42d4-a721-d3d064866224" xlink:to="loc_us-gaap_PaymentsToAcquireProductiveAssets_dd0c43b5-816b-4146-a288-49fdc9e30317" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONGeographicInformationDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#SEGMENTANDGEOGRAPHICINFORMATIONGeographicInformationDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/SEGMENTANDGEOGRAPHICINFORMATIONGeographicInformationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_4afcb2a1-916f-46ff-b6dc-54a467fc3fc5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_30f81042-165f-459c-94e1-57f50aee6248" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_4afcb2a1-916f-46ff-b6dc-54a467fc3fc5" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_30f81042-165f-459c-94e1-57f50aee6248" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_eb340409-dedf-4a73-a25a-d033e5841cf6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_30f81042-165f-459c-94e1-57f50aee6248" xlink:to="loc_srt_StatementGeographicalAxis_eb340409-dedf-4a73-a25a-d033e5841cf6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_eb340409-dedf-4a73-a25a-d033e5841cf6_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_eb340409-dedf-4a73-a25a-d033e5841cf6" xlink:to="loc_srt_SegmentGeographicalDomain_eb340409-dedf-4a73-a25a-d033e5841cf6_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_edecfe6d-4f67-4927-9251-f058439a7206" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_eb340409-dedf-4a73-a25a-d033e5841cf6" xlink:to="loc_srt_SegmentGeographicalDomain_edecfe6d-4f67-4927-9251-f058439a7206" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_bc8ff8aa-d4f5-40eb-bae0-3b4a7119a8a3" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_edecfe6d-4f67-4927-9251-f058439a7206" xlink:to="loc_country_US_bc8ff8aa-d4f5-40eb-bae0-3b4a7119a8a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_NL_b356f12c-d8f9-4d37-b4f2-1b7f1548e0d0" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_NL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_edecfe6d-4f67-4927-9251-f058439a7206" xlink:to="loc_country_NL_b356f12c-d8f9-4d37-b4f2-1b7f1548e0d0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_OtherThanUnitedStatesAndNetherlandsMember_9a4c691e-b5f9-417c-8a84-e9827ab28982" xlink:href="notv-20240331.xsd#notv_OtherThanUnitedStatesAndNetherlandsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_edecfe6d-4f67-4927-9251-f058439a7206" xlink:to="loc_notv_OtherThanUnitedStatesAndNetherlandsMember_9a4c691e-b5f9-417c-8a84-e9827ab28982" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c2611165-ae9f-49f5-be0f-c9c247c3bc33" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_4afcb2a1-916f-46ff-b6dc-54a467fc3fc5" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_c2611165-ae9f-49f5-be0f-c9c247c3bc33" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_a613fa9e-3303-45c5-b880-963541ea41ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_4afcb2a1-916f-46ff-b6dc-54a467fc3fc5" xlink:to="loc_us-gaap_NoncurrentAssets_a613fa9e-3303-45c5-b880-963541ea41ad" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/BUSINESSCOMBINATIONSNarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#BUSINESSCOMBINATIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/BUSINESSCOMBINATIONSNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_98d06eb0-874b-4339-9a09-21aac51cb27a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_98d06eb0-874b-4339-9a09-21aac51cb27a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_564136cc-272c-4321-9d9b-45cccefd7fe8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_98d06eb0-874b-4339-9a09-21aac51cb27a" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_564136cc-272c-4321-9d9b-45cccefd7fe8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_564136cc-272c-4321-9d9b-45cccefd7fe8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_564136cc-272c-4321-9d9b-45cccefd7fe8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_564136cc-272c-4321-9d9b-45cccefd7fe8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_564136cc-272c-4321-9d9b-45cccefd7fe8" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_PlatoBiopharmaIncMember_d403f7e4-914d-4242-bec7-ed6a4884758d" xlink:href="notv-20240331.xsd#notv_PlatoBiopharmaIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_PlatoBiopharmaIncMember_d403f7e4-914d-4242-bec7-ed6a4884758d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_EnvigoRmsHoldingCorporationMember_717f5550-d09f-4833-a222-996e95c70d75" xlink:href="notv-20240331.xsd#notv_EnvigoRmsHoldingCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_EnvigoRmsHoldingCorporationMember_717f5550-d09f-4833-a222-996e95c70d75" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_RobinsonServicesInc.Member_1040b62c-01b5-4a6c-a8fb-4cc37cb66604" xlink:href="notv-20240331.xsd#notv_RobinsonServicesInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_RobinsonServicesInc.Member_1040b62c-01b5-4a6c-a8fb-4cc37cb66604" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_IntegratedLaboratorySystemsLlcMember_1e62f384-cd32-4a48-8cb2-1a2673c4d1c4" xlink:href="notv-20240331.xsd#notv_IntegratedLaboratorySystemsLlcMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_IntegratedLaboratorySystemsLlcMember_1e62f384-cd32-4a48-8cb2-1a2673c4d1c4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_OrientBioresourceCenterIncMember_ac97ff47-c0e9-4914-8ba9-81e2c38ce8d3" xlink:href="notv-20240331.xsd#notv_OrientBioresourceCenterIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_OrientBioresourceCenterIncMember_ac97ff47-c0e9-4914-8ba9-81e2c38ce8d3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_HistionLlcAcquisitionMember_1e41b3c2-a305-4e47-808a-0341670609e3" xlink:href="notv-20240331.xsd#notv_HistionLlcAcquisitionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_HistionLlcAcquisitionMember_1e41b3c2-a305-4e47-808a-0341670609e3" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ProtypiaInc.Member_b4a93cee-139b-452d-a00f-ee419fdad043" xlink:href="notv-20240331.xsd#notv_ProtypiaInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_eb426d69-78f6-40c0-8c1f-7f854aa0738c" xlink:to="loc_notv_ProtypiaInc.Member_b4a93cee-139b-452d-a00f-ee419fdad043" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_04bf6e18-48db-4505-940b-8ba752a75dc9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_98d06eb0-874b-4339-9a09-21aac51cb27a" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_04bf6e18-48db-4505-940b-8ba752a75dc9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_04bf6e18-48db-4505-940b-8ba752a75dc9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_04bf6e18-48db-4505-940b-8ba752a75dc9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_04bf6e18-48db-4505-940b-8ba752a75dc9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d978162d-d476-42b0-a455-9334eb7a54d4" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_04bf6e18-48db-4505-940b-8ba752a75dc9" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d978162d-d476-42b0-a455-9334eb7a54d4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_b796b962-c3a3-42d8-a7c0-b64b764acd86" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d978162d-d476-42b0-a455-9334eb7a54d4" xlink:to="loc_us-gaap_CustomerRelationshipsMember_b796b962-c3a3-42d8-a7c0-b64b764acd86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntellectualPropertyMember_91423b0e-88fc-40fe-92b1-1b7c144e8622" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntellectualPropertyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_d978162d-d476-42b0-a455-9334eb7a54d4" xlink:to="loc_us-gaap_IntellectualPropertyMember_91423b0e-88fc-40fe-92b1-1b7c144e8622" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_1fd45278-e358-4e58-8636-1db4240198f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_98d06eb0-874b-4339-9a09-21aac51cb27a" xlink:to="loc_us-gaap_DebtInstrumentAxis_1fd45278-e358-4e58-8636-1db4240198f7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_1fd45278-e358-4e58-8636-1db4240198f7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_1fd45278-e358-4e58-8636-1db4240198f7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_1fd45278-e358-4e58-8636-1db4240198f7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_64ba9226-0ec5-4327-916d-40fc25d400ff" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_1fd45278-e358-4e58-8636-1db4240198f7" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_64ba9226-0ec5-4327-916d-40fc25d400ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_PromissoryNoteMember_c24e74ab-97bf-42b3-8cdc-38acc199b334" xlink:href="notv-20240331.xsd#notv_PromissoryNoteMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_64ba9226-0ec5-4327-916d-40fc25d400ff" xlink:to="loc_notv_PromissoryNoteMember_c24e74ab-97bf-42b3-8cdc-38acc199b334" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_567b74cf-2f01-49b1-9128-0445f4d40def" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_567b74cf-2f01-49b1-9128-0445f4d40def" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_93e88c06-27d4-4d15-a676-15ca462c1797" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued_93e88c06-27d4-4d15-a676-15ca462c1797" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned_4a1c843f-aea6-4746-8989-0d1c14977a4d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessAcquisitionEquityInterestIssuedOrIssuableValueAssigned_4a1c843f-aea6-4746-8989-0d1c14977a4d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_7bf95edc-24ad-414e-8799-307695f18dbc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_7bf95edc-24ad-414e-8799-307695f18dbc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_1abec506-cc99-4c8b-af30-a37b02c6961d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_1abec506-cc99-4c8b-af30-a37b02c6961d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_90f2b1e0-3db8-455c-9940-f764ebaecc8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_90f2b1e0-3db8-455c-9940-f764ebaecc8d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_93f22f2d-b204-4905-aab5-e5fb9ac19a17" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_93f22f2d-b204-4905-aab5-e5fb9ac19a17" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_f46bf1a1-3eb8-4519-871f-f38c3dc6ac6b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_f46bf1a1-3eb8-4519-871f-f38c3dc6ac6b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_StockOptionsPricePerShare_ad88b717-3897-41cc-8cc1-bb17196cb1e7" xlink:href="notv-20240331.xsd#notv_StockOptionsPricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_StockOptionsPricePerShare_ad88b717-3897-41cc-8cc1-bb17196cb1e7" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharePrice_9a265983-2e58-4b08-87f1-71b5b8b64463" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SharePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_SharePrice_9a265983-2e58-4b08-87f1-71b5b8b64463" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ValueOfOption_a5569ddb-d79b-48db-acd8-c455411590a0" xlink:href="notv-20240331.xsd#notv_ValueOfOption"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_ValueOfOption_a5569ddb-d79b-48db-acd8-c455411590a0" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ValueOfOptionsExcludedFromPurchasePrice_098b7194-80a1-415c-a27b-51b155ea7253" xlink:href="notv-20240331.xsd#notv_ValueOfOptionsExcludedFromPurchasePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_ValueOfOptionsExcludedFromPurchasePrice_098b7194-80a1-415c-a27b-51b155ea7253" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_0863a43d-533c-4f7d-bffc-5762959a3c72" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredEquityInterestsIssuedAndIssuable_0863a43d-533c-4f7d-bffc-5762959a3c72" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_7ea7f623-aa68-4ed5-b58a-3e7ea9dcd50d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_NetIncomeLoss_7ea7f623-aa68-4ed5-b58a-3e7ea9dcd50d" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromAcquisition_f98a246d-3371-4365-a60d-35bd3e8de4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_UnrecognizedTaxBenefitsIncreasesResultingFromAcquisition_f98a246d-3371-4365-a60d-35bd3e8de4bf" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_156cedca-6b78-4dd8-a96d-a7e72685bb04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_156cedca-6b78-4dd8-a96d-a7e72685bb04" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EscrowDepositDisbursementsRelatedToPropertyAcquisition1_af5cc275-8b8f-442c-84ac-4975ad72acca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_EscrowDepositDisbursementsRelatedToPropertyAcquisition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_EscrowDepositDisbursementsRelatedToPropertyAcquisition1_af5cc275-8b8f-442c-84ac-4975ad72acca" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_BusinessCombinationSettlementOfPreexistingRelationship_6a86132e-fab7-4aae-999a-2c11c7a3ac51" xlink:href="notv-20240331.xsd#notv_BusinessCombinationSettlementOfPreexistingRelationship"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_BusinessCombinationSettlementOfPreexistingRelationship_6a86132e-fab7-4aae-999a-2c11c7a3ac51" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_45716a64-ca5a-46c1-9126-e1d385288be5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredLiabilitiesIncurred_45716a64-ca5a-46c1-9126-e1d385288be5" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGainOrLoss_8f2cafff-f4b8-49ac-b924-7d5a384e75c3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGainOrLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeRemeasurementGainOrLoss_8f2cafff-f4b8-49ac-b924-7d5a384e75c3" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_BusinessCombinationPeriodForPaymentOfConsideration_fa07009a-7654-4c84-a8cb-4d9ab357f50b" xlink:href="notv-20240331.xsd#notv_BusinessCombinationPeriodForPaymentOfConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_BusinessCombinationPeriodForPaymentOfConsideration_fa07009a-7654-4c84-a8cb-4d9ab357f50b" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_BusinessCombinationConsiderationPaymentPeriodExtension_fa5eea1d-410c-42c0-b913-f1d89381614c" xlink:href="notv-20240331.xsd#notv_BusinessCombinationConsiderationPaymentPeriodExtension"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_3e6f4b0c-6b11-436f-933a-74c62ac8c511" xlink:to="loc_notv_BusinessCombinationConsiderationPaymentPeriodExtension_fa5eea1d-410c-42c0-b913-f1d89381614c" xlink:type="arc" order="21"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/BUSINESSCOMBINATIONSFairvalueofassetsacquiredandliabilitiesassumedDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#BUSINESSCOMBINATIONSFairvalueofassetsacquiredandliabilitiesassumedDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/BUSINESSCOMBINATIONSFairvalueofassetsacquiredandliabilitiesassumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_546fee0f-ea82-45d4-9377-a2b06ccb810c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8dda3ed0-9731-4fbe-823d-4e556defab8d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_546fee0f-ea82-45d4-9377-a2b06ccb810c" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8dda3ed0-9731-4fbe-823d-4e556defab8d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_5df4c69e-e0c6-49cb-968a-a94e1c33b120" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_8dda3ed0-9731-4fbe-823d-4e556defab8d" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_5df4c69e-e0c6-49cb-968a-a94e1c33b120" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5df4c69e-e0c6-49cb-968a-a94e1c33b120_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5df4c69e-e0c6-49cb-968a-a94e1c33b120" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_5df4c69e-e0c6-49cb-968a-a94e1c33b120_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4fd83db1-3c04-4e5b-9685-04ff6d0f866d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_5df4c69e-e0c6-49cb-968a-a94e1c33b120" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4fd83db1-3c04-4e5b-9685-04ff6d0f866d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ProtypiaInc.Member_d2453437-d8fc-4ef8-ac98-b80e47438ef5" xlink:href="notv-20240331.xsd#notv_ProtypiaInc.Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4fd83db1-3c04-4e5b-9685-04ff6d0f866d" xlink:to="loc_notv_ProtypiaInc.Member_d2453437-d8fc-4ef8-ac98-b80e47438ef5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_546fee0f-ea82-45d4-9377-a2b06ccb810c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_740c3e0e-d4d2-452a-b69b-873522d5ba85" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:to="loc_us-gaap_Goodwill_740c3e0e-d4d2-452a-b69b-873522d5ba85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_905c0502-de66-4f56-ab06-5814af685d69" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibleAssetsOtherThanGoodwill_905c0502-de66-4f56-ab06-5814af685d69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_ab23d2a0-3451-4b08-8784-57a8a2e334fb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesOther_ab23d2a0-3451-4b08-8784-57a8a2e334fb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_2ccfd51a-74a5-44ad-950e-8e09f8d3742a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_2ccfd51a-74a5-44ad-950e-8e09f8d3742a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_6a2f7f05-4fd5-4cf5-87ba-65c8ae63ad6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNetAbstract_02bf27b6-b46b-4720-b110-7567a996a5ed" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_6a2f7f05-4fd5-4cf5-87ba-65c8ae63ad6a" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/INTANGIBLEASSETSIntangibleAssetsnetbymajorclassDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#INTANGIBLEASSETSIntangibleAssetsnetbymajorclassDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/INTANGIBLEASSETSIntangibleAssetsnetbymajorclassDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_295537a1-c62d-4d10-a1ab-26029287a645" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_389f087f-1f3c-487e-acde-54b14f1eb9fe" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_295537a1-c62d-4d10-a1ab-26029287a645" xlink:to="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_389f087f-1f3c-487e-acde-54b14f1eb9fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e790a1bf-f569-4eae-b733-555dc431a422" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfFiniteLivedIntangibleAssetsTable_389f087f-1f3c-487e-acde-54b14f1eb9fe" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e790a1bf-f569-4eae-b733-555dc431a422" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e790a1bf-f569-4eae-b733-555dc431a422_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e790a1bf-f569-4eae-b733-555dc431a422" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_e790a1bf-f569-4eae-b733-555dc431a422_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5424e3a5-4e20-474b-b59a-c92a802d4c78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_e790a1bf-f569-4eae-b733-555dc431a422" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5424e3a5-4e20-474b-b59a-c92a802d4c78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_c9a050a8-bb8a-4fc7-a6c2-131b17a821a1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5424e3a5-4e20-474b-b59a-c92a802d4c78" xlink:to="loc_us-gaap_CustomerRelationshipsMember_c9a050a8-bb8a-4fc7-a6c2-131b17a821a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntellectualPropertyMember_fdb7a16b-fc41-475d-9213-978a4ce87d6c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IntellectualPropertyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5424e3a5-4e20-474b-b59a-c92a802d4c78" xlink:to="loc_us-gaap_IntellectualPropertyMember_fdb7a16b-fc41-475d-9213-978a4ce87d6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_e4376cf2-0270-4244-8df5-d5173efc077d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_5424e3a5-4e20-474b-b59a-c92a802d4c78" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_e4376cf2-0270-4244-8df5-d5173efc077d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsGross_72362cd0-cd37-40ff-889d-cad71a2377df" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_295537a1-c62d-4d10-a1ab-26029287a645" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsGross_72362cd0-cd37-40ff-889d-cad71a2377df" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a0956744-d4c4-4bc8-8f7f-40dd9c5e79fd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_295537a1-c62d-4d10-a1ab-26029287a645" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsAccumulatedAmortization_a0956744-d4c4-4bc8-8f7f-40dd9c5e79fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsNet_4690058d-1bec-4851-b3d9-e5efbbb10743" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_FiniteLivedIntangibleAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsLineItems_295537a1-c62d-4d10-a1ab-26029287a645" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsNet_4690058d-1bec-4851-b3d9-e5efbbb10743" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/DEBTScheduleoflongtermdebtDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#DEBTScheduleoflongtermdebtDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/DEBTScheduleoflongtermdebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_46680c3e-ac0b-492f-be0c-58563409ec04" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_DebtInstrumentTable_46680c3e-ac0b-492f-be0c-58563409ec04" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_2b63dd28-34e5-407e-9401-21a0019ea24c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_46680c3e-ac0b-492f-be0c-58563409ec04" xlink:to="loc_us-gaap_DebtInstrumentAxis_2b63dd28-34e5-407e-9401-21a0019ea24c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_2b63dd28-34e5-407e-9401-21a0019ea24c_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_2b63dd28-34e5-407e-9401-21a0019ea24c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_2b63dd28-34e5-407e-9401-21a0019ea24c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_2b63dd28-34e5-407e-9401-21a0019ea24c" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteBolderBiopathMember_700f51bf-754a-48b1-801c-7090edee3c8f" xlink:href="notv-20240331.xsd#notv_SellerNoteBolderBiopathMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_SellerNoteBolderBiopathMember_700f51bf-754a-48b1-801c-7090edee3c8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNotePreClinicalResearchServicesMember_95174714-2bdd-436a-9058-08eb0b0e2c00" xlink:href="notv-20240331.xsd#notv_SellerNotePreClinicalResearchServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_SellerNotePreClinicalResearchServicesMember_95174714-2bdd-436a-9058-08eb0b0e2c00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerPayableOrientBioResourceCenterMember_49db169d-1cfa-46f9-8199-d5297211cce6" xlink:href="notv-20240331.xsd#notv_SellerPayableOrientBioResourceCenterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_SellerPayableOrientBioResourceCenterMember_49db169d-1cfa-46f9-8199-d5297211cce6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteHistionMember_3cf6c96e-2deb-4a08-8d98-63f72a7a1b64" xlink:href="notv-20240331.xsd#notv_SellerNoteHistionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_SellerNoteHistionMember_3cf6c96e-2deb-4a08-8d98-63f72a7a1b64" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteProtypiaMember_c6333eb0-2524-44e6-8fa6-bb362d6e5960" xlink:href="notv-20240331.xsd#notv_SellerNoteProtypiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_SellerNoteProtypiaMember_c6333eb0-2524-44e6-8fa6-bb362d6e5960" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember_4936d6cb-a58e-4bc1-b98e-e82887c4fd3c" xlink:href="notv-20240331.xsd#notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember_4936d6cb-a58e-4bc1-b98e-e82887c4fd3c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ConvertibleSeniorNotesDue2027Member_19a22d21-a131-441f-bea6-850484ced1f1" xlink:href="notv-20240331.xsd#notv_ConvertibleSeniorNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_ConvertibleSeniorNotesDue2027Member_19a22d21-a131-441f-bea6-850484ced1f1" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_TermLoanFacilityInitialDdtlAndIncrementalTermLoansMember_07b1a124-cb04-4472-998a-2e3b7fac4832" xlink:href="notv-20240331.xsd#notv_TermLoanFacilityInitialDdtlAndIncrementalTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_ef684c32-0536-4c12-96d3-626214628c08" xlink:to="loc_notv_TermLoanFacilityInitialDdtlAndIncrementalTermLoansMember_07b1a124-cb04-4472-998a-2e3b7fac4832" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_548ee909-4853-41fe-aebd-210475ccdee7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_548ee909-4853-41fe-aebd-210475ccdee7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnamortizedDebtIssuanceExpense_3549491a-046f-4868-b179-7617f6cd95a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnamortizedDebtIssuanceExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_UnamortizedDebtIssuanceExpense_3549491a-046f-4868-b179-7617f6cd95a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_d1dd9ee7-9ee8-4173-9c39-3d89b62e4da9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_LongTermDebt_d1dd9ee7-9ee8-4173-9c39-3d89b62e4da9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_610417be-f8ac-4ae3-8c2e-e02e0d6c6625" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_LongTermDebtCurrent_610417be-f8ac-4ae3-8c2e-e02e0d6c6625" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_ba3a0c3d-8b17-4a7b-aa8f-bed0498fb178" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_6f46eb82-95df-4b7d-b6a3-d932ace7e54c" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_ba3a0c3d-8b17-4a7b-aa8f-bed0498fb178" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/DEBTNarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#DEBTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/DEBTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_9ad3de1f-7bb7-40c1-939f-18fd53d058a3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_DebtInstrumentAxis_9ad3de1f-7bb7-40c1-939f-18fd53d058a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_9ad3de1f-7bb7-40c1-939f-18fd53d058a3_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_9ad3de1f-7bb7-40c1-939f-18fd53d058a3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_9ad3de1f-7bb7-40c1-939f-18fd53d058a3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_9ad3de1f-7bb7-40c1-939f-18fd53d058a3" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNotePlatoBiopharmaMember_18804c44-9619-4990-89c1-8abf5424b7a1" xlink:href="notv-20240331.xsd#notv_SellerNotePlatoBiopharmaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerNotePlatoBiopharmaMember_18804c44-9619-4990-89c1-8abf5424b7a1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerPayableOrientBioResourceCenterMember_e3e5d65e-cd59-40e1-a55e-1b162b193751" xlink:href="notv-20240331.xsd#notv_SellerPayableOrientBioResourceCenterMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerPayableOrientBioResourceCenterMember_e3e5d65e-cd59-40e1-a55e-1b162b193751" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteHistionMember_1d76f7c3-6136-4ab4-aaa2-6acebb575952" xlink:href="notv-20240331.xsd#notv_SellerNoteHistionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerNoteHistionMember_1d76f7c3-6136-4ab4-aaa2-6acebb575952" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteProtypiaMember_4dfd3e46-e781-422b-8d30-67c3a80abb9b" xlink:href="notv-20240331.xsd#notv_SellerNoteProtypiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerNoteProtypiaMember_4dfd3e46-e781-422b-8d30-67c3a80abb9b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ConvertibleSeniorNotesDue2027Member_ffe2ed17-0d3f-473e-9bfb-d334745db911" xlink:href="notv-20240331.xsd#notv_ConvertibleSeniorNotesDue2027Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_ConvertibleSeniorNotesDue2027Member_ffe2ed17-0d3f-473e-9bfb-d334745db911" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember_770a5e25-41cf-4cd0-889e-a9e1498daf2c" xlink:href="notv-20240331.xsd#notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_EconomicInjuryDisasterLoanSmallBusinessAdministrationMember_770a5e25-41cf-4cd0-889e-a9e1498daf2c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNotePreClinicalResearchServicesMember_db6f0f2c-99ec-494c-beea-2e3493807d0e" xlink:href="notv-20240331.xsd#notv_SellerNotePreClinicalResearchServicesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerNotePreClinicalResearchServicesMember_db6f0f2c-99ec-494c-beea-2e3493807d0e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SellerNoteBolderBiopathMember_48cbc81b-4b8e-4ad1-8834-e482d63cfe83" xlink:href="notv-20240331.xsd#notv_SellerNoteBolderBiopathMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_5333fe23-ee73-4a80-9c4f-b18ea7e4a6bb" xlink:to="loc_notv_SellerNoteBolderBiopathMember_48cbc81b-4b8e-4ad1-8834-e482d63cfe83" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeAxis_4baac57b-23b1-4e38-8a27-e62de9fb55cf" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_ShortTermDebtTypeAxis_4baac57b-23b1-4e38-8a27-e62de9fb55cf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_4baac57b-23b1-4e38-8a27-e62de9fb55cf_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_4baac57b-23b1-4e38-8a27-e62de9fb55cf" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_4baac57b-23b1-4e38-8a27-e62de9fb55cf_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShortTermDebtTypeDomain_5267a1a8-b781-4458-989f-edffe8595dfd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShortTermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ShortTermDebtTypeAxis_4baac57b-23b1-4e38-8a27-e62de9fb55cf" xlink:to="loc_us-gaap_ShortTermDebtTypeDomain_5267a1a8-b781-4458-989f-edffe8595dfd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_dcf3b912-8005-470d-bbcf-81ea25441f28" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShortTermDebtTypeDomain_5267a1a8-b781-4458-989f-edffe8595dfd" xlink:to="loc_us-gaap_UnsecuredDebtMember_dcf3b912-8005-470d-bbcf-81ea25441f28" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_0fce3697-5aef-4fbf-8579-5390ac0c6bb8" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AdjustmentsForNewAccountingPronouncementsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_0fce3697-5aef-4fbf-8579-5390ac0c6bb8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_0fce3697-5aef-4fbf-8579-5390ac0c6bb8_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_0fce3697-5aef-4fbf-8579-5390ac0c6bb8" xlink:to="loc_us-gaap_TypeOfAdoptionMember_0fce3697-5aef-4fbf-8579-5390ac0c6bb8_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfAdoptionMember_61ac8a6e-46b1-4707-940a-a17aa4a575cb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_TypeOfAdoptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AdjustmentsForNewAccountingPronouncementsAxis_0fce3697-5aef-4fbf-8579-5390ac0c6bb8" xlink:to="loc_us-gaap_TypeOfAdoptionMember_61ac8a6e-46b1-4707-940a-a17aa4a575cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccountingStandardsUpdate202006Member_fd955e87-89b2-4edd-84e3-a876ff5b2339" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AccountingStandardsUpdate202006Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfAdoptionMember_61ac8a6e-46b1-4707-940a-a17aa4a575cb" xlink:to="loc_us-gaap_AccountingStandardsUpdate202006Member_fd955e87-89b2-4edd-84e3-a876ff5b2339" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_b118bf87-df50-4216-9c55-9bc8f1e8b255" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_7ce1e0bb-dce4-4cc7-9e96-b4e1b32ab9ae" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_b118bf87-df50-4216-9c55-9bc8f1e8b255" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_981e1138-7dd0-4b20-a6ee-acee5becb418" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_b118bf87-df50-4216-9c55-9bc8f1e8b255" xlink:to="loc_us-gaap_UnsecuredDebtMember_981e1138-7dd0-4b20-a6ee-acee5becb418" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_CreditFacilityAxis_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7" xlink:to="loc_us-gaap_CreditFacilityDomain_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_48170b1c-bc50-455f-99eb-7b632c1e7a8c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_a0286e2e-28cc-4f34-81fb-3cd9fc50e5e7" xlink:to="loc_us-gaap_CreditFacilityDomain_48170b1c-bc50-455f-99eb-7b632c1e7a8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:href="notv-20240331.xsd#notv_AmendedAndRestatedCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_48170b1c-bc50-455f-99eb-7b632c1e7a8c" xlink:to="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_TermLoanMember_1691c48e-a56b-40b2-9016-e3379adf5500" xlink:href="notv-20240331.xsd#notv_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_notv_TermLoanMember_1691c48e-a56b-40b2-9016-e3379adf5500" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DelayedDrawTermLoanMember_9cb99a75-c85d-4c4d-8095-2f4a877292d5" xlink:href="notv-20240331.xsd#notv_DelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_notv_DelayedDrawTermLoanMember_9cb99a75-c85d-4c4d-8095-2f4a877292d5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_CreditFacilityTermLoanAndDelayedDrawTermLoanMember_9df50f2f-bd64-4200-ad59-33148dd4f560" xlink:href="notv-20240331.xsd#notv_CreditFacilityTermLoanAndDelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_notv_CreditFacilityTermLoanAndDelayedDrawTermLoanMember_9df50f2f-bd64-4200-ad59-33148dd4f560" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_a1db4547-e441-49c1-bd6a-300830804372" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_a1db4547-e441-49c1-bd6a-300830804372" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_NewDelayedDrawTermLoanMember_97719dea-8a0f-498a-a28e-c9c05ef7f294" xlink:href="notv-20240331.xsd#notv_NewDelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_notv_NewDelayedDrawTermLoanMember_97719dea-8a0f-498a-a28e-c9c05ef7f294" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_AdditionalTermLoansMember_4396939f-8de8-4caa-9580-ad62954bdebe" xlink:href="notv-20240331.xsd#notv_AdditionalTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_AmendedAndRestatedCreditAgreementMember_45858fb2-e136-4a1b-bd7f-ed460212b848" xlink:to="loc_notv_AdditionalTermLoansMember_4396939f-8de8-4caa-9580-ad62954bdebe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_63e58cd7-06ce-458a-a526-e4e2e675c3c2" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_srt_RangeAxis_63e58cd7-06ce-458a-a526-e4e2e675c3c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_63e58cd7-06ce-458a-a526-e4e2e675c3c2_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_63e58cd7-06ce-458a-a526-e4e2e675c3c2" xlink:to="loc_srt_RangeMember_63e58cd7-06ce-458a-a526-e4e2e675c3c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_d93ab633-f284-482e-9065-d88b12f3b1ab" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_63e58cd7-06ce-458a-a526-e4e2e675c3c2" xlink:to="loc_srt_RangeMember_d93ab633-f284-482e-9065-d88b12f3b1ab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_41e1a43f-76ab-43c8-ab15-93ee8b8033b6" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d93ab633-f284-482e-9065-d88b12f3b1ab" xlink:to="loc_srt_MaximumMember_41e1a43f-76ab-43c8-ab15-93ee8b8033b6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_b23680a6-756c-4666-821e-ebda3f1a00cc" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_d93ab633-f284-482e-9065-d88b12f3b1ab" xlink:to="loc_srt_MinimumMember_b23680a6-756c-4666-821e-ebda3f1a00cc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateAxis_e175949e-5af6-4e5d-b13a-99c0a4c02245" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_VariableRateAxis_e175949e-5af6-4e5d-b13a-99c0a4c02245" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_e175949e-5af6-4e5d-b13a-99c0a4c02245_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VariableRateAxis_e175949e-5af6-4e5d-b13a-99c0a4c02245" xlink:to="loc_us-gaap_VariableRateDomain_e175949e-5af6-4e5d-b13a-99c0a4c02245_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_VariableRateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VariableRateAxis_e175949e-5af6-4e5d-b13a-99c0a4c02245" xlink:to="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BaseRateMember_6613be4b-5645-496d-a587-d084763b449e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BaseRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:to="loc_us-gaap_BaseRateMember_6613be4b-5645-496d-a587-d084763b449e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SecuredOvernightFinancingRateSOFRMember_153786aa-d05c-451f-a3eb-67c43a5a3eec" xlink:href="notv-20240331.xsd#notv_SecuredOvernightFinancingRateSOFRMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:to="loc_notv_SecuredOvernightFinancingRateSOFRMember_153786aa-d05c-451f-a3eb-67c43a5a3eec" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LondonInterbankOfferedRateMember_a6596a7e-20c8-4cfe-a9be-83daa56992e5" xlink:href="notv-20240331.xsd#notv_LondonInterbankOfferedRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:to="loc_notv_LondonInterbankOfferedRateMember_a6596a7e-20c8-4cfe-a9be-83daa56992e5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrimeRateMember_32d8738d-32de-45f3-b7a9-9105644d8744" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PrimeRateMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VariableRateDomain_027330e7-cf1b-4235-91f9-ca0f871859bd" xlink:to="loc_us-gaap_PrimeRateMember_32d8738d-32de-45f3-b7a9-9105644d8744" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationAxis_8d343618-62bc-42f7-9587-c802349be47d" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_us-gaap_IncomeStatementLocationAxis_8d343618-62bc-42f7-9587-c802349be47d" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_8d343618-62bc-42f7-9587-c802349be47d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_8d343618-62bc-42f7-9587-c802349be47d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_8d343618-62bc-42f7-9587-c802349be47d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementLocationDomain_fc789b71-95a2-4c4f-bf56-cc69b317db30" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementLocationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementLocationAxis_8d343618-62bc-42f7-9587-c802349be47d" xlink:to="loc_us-gaap_IncomeStatementLocationDomain_fc789b71-95a2-4c4f-bf56-cc69b317db30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIncomeMember_d4bae938-7cbb-41c0-80ab-f57b08e01b59" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OtherIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeStatementLocationDomain_fc789b71-95a2-4c4f-bf56-cc69b317db30" xlink:to="loc_us-gaap_OtherIncomeMember_d4bae938-7cbb-41c0-80ab-f57b08e01b59" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantAxis_771a1a7e-4a65-48ea-a948-d20b2a8e6598" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_4b3a90bf-5312-403c-b975-9cdef5ea26a5" xlink:to="loc_notv_DebtInstrumentCovenantAxis_771a1a7e-4a65-48ea-a948-d20b2a8e6598" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantDomain_771a1a7e-4a65-48ea-a948-d20b2a8e6598_default" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_notv_DebtInstrumentCovenantAxis_771a1a7e-4a65-48ea-a948-d20b2a8e6598" xlink:to="loc_notv_DebtInstrumentCovenantDomain_771a1a7e-4a65-48ea-a948-d20b2a8e6598_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_notv_DebtInstrumentCovenantAxis_771a1a7e-4a65-48ea-a948-d20b2a8e6598" xlink:to="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityInitialLeverageRatioMember_9c05fb2f-6e3c-4e26-8e59-9f3f21304962" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityInitialLeverageRatioMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:to="loc_notv_LineOfCreditFacilityInitialLeverageRatioMember_9c05fb2f-6e3c-4e26-8e59-9f3f21304962" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingSeptember302023Member_23ed2bf3-1dbe-4180-87e6-7a98543033a0" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingSeptember302023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:to="loc_notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingSeptember302023Member_23ed2bf3-1dbe-4180-87e6-7a98543033a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingMarch312025Member_8b2e875c-07ec-41f4-8ad2-900ff11d4e77" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingMarch312025Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:to="loc_notv_LineOfCreditFacilityLeverageRatioToBeMaintainedBeginningQuarterEndingMarch312025Member_8b2e875c-07ec-41f4-8ad2-900ff11d4e77" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedDuringFirstAnniversaryMember_31521828-c740-4843-88fa-3a7e9681fd29" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedDuringFirstAnniversaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:to="loc_notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedDuringFirstAnniversaryMember_31521828-c740-4843-88fa-3a7e9681fd29" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedFromAndAfterFirstAnniversaryMember_c714fca8-ca53-44b9-b876-f278ce48fddc" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedFromAndAfterFirstAnniversaryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_notv_DebtInstrumentCovenantDomain_64dc5b01-fc0a-461d-9a1b-3eaaf2f9ff03" xlink:to="loc_notv_LineOfCreditFacilityMinimumFixedChargeCoverageRatioToBeMaintainedFromAndAfterFirstAnniversaryMember_c714fca8-ca53-44b9-b876-f278ce48fddc" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_e8c1420d-8764-474b-bbb0-22d3e413c2ad" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_LinesOfCreditCurrent_e8c1420d-8764-474b-bbb0-22d3e413c2ad" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ProceedsFromDelayedDrawTermLoan_24181ac8-e897-435b-b3a2-8a581fac24bf" xlink:href="notv-20240331.xsd#notv_ProceedsFromDelayedDrawTermLoan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_ProceedsFromDelayedDrawTermLoan_24181ac8-e897-435b-b3a2-8a581fac24bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_RepaymentOfLinesOfCredit_d1845857-4c62-4263-b4dd-3c088a251cb5" xlink:href="notv-20240331.xsd#notv_RepaymentOfLinesOfCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_RepaymentOfLinesOfCredit_d1845857-4c62-4263-b4dd-3c088a251cb5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_52deeb33-a729-45d2-bbef-b1ea95e19269" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_52deeb33-a729-45d2-bbef-b1ea95e19269" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_MaximumTermForDrawingLoanFacility_90ffc6f1-8455-4976-a4b8-1017a7e6267d" xlink:href="notv-20240331.xsd#notv_MaximumTermForDrawingLoanFacility"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_MaximumTermForDrawingLoanFacility_90ffc6f1-8455-4976-a4b8-1017a7e6267d" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_f49c6c89-f280-428b-bab3-c18d20ef44e7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity_f49c6c89-f280-428b-bab3-c18d20ef44e7" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3ed32a1c-2349-4148-849d-d7346c326bf3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentBasisSpreadOnVariableRate1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentBasisSpreadOnVariableRate1_3ed32a1c-2349-4148-849d-d7346c326bf3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentVariableInterestFloorRate_3d668df0-03a6-4f6f-82f0-bc2c3976348a" xlink:href="notv-20240331.xsd#notv_DebtInstrumentVariableInterestFloorRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentVariableInterestFloorRate_3d668df0-03a6-4f6f-82f0-bc2c3976348a" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_862fab45-49d3-45e3-adc2-9c03076cdf25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_862fab45-49d3-45e3-adc2-9c03076cdf25" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_2df00202-bce4-460d-9107-72f9dbd6922a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage_2df00202-bce4-460d-9107-72f9dbd6922a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityAnnualPrincipalPaymentPercentage_a4e2a2bb-d3ae-4344-abc7-b0d53c40d6e6" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityAnnualPrincipalPaymentPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_LineOfCreditFacilityAnnualPrincipalPaymentPercentage_a4e2a2bb-d3ae-4344-abc7-b0d53c40d6e6" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityPrepaymentPremiumPercentage_98abebaf-1064-4af0-9623-452171c22b1a" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityPrepaymentPremiumPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_LineOfCreditFacilityPrepaymentPremiumPercentage_98abebaf-1064-4af0-9623-452171c22b1a" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityThresholdSecuredLeverageRatio_9988624e-205d-4c67-b6b0-874876635455" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityThresholdSecuredLeverageRatio"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_LineOfCreditFacilityThresholdSecuredLeverageRatio_9988624e-205d-4c67-b6b0-874876635455" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_dee09ab5-f438-4f77-b3de-3b282f021e1f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_dee09ab5-f438-4f77-b3de-3b282f021e1f" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentNumberOfDaysAfterEndOfEachMonthUnauditedFinancialsRequiredToBePrepared_6f917af6-a2e6-4000-bda2-d0e3345659bc" xlink:href="notv-20240331.xsd#notv_DebtInstrumentNumberOfDaysAfterEndOfEachMonthUnauditedFinancialsRequiredToBePrepared"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentNumberOfDaysAfterEndOfEachMonthUnauditedFinancialsRequiredToBePrepared_6f917af6-a2e6-4000-bda2-d0e3345659bc" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentNumberOfBusinessDaysFromEndOfEachMonthToPrepareCashFlowStatement_19eabc62-9742-48db-9773-1dc74704888e" xlink:href="notv-20240331.xsd#notv_DebtInstrumentNumberOfBusinessDaysFromEndOfEachMonthToPrepareCashFlowStatement"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentNumberOfBusinessDaysFromEndOfEachMonthToPrepareCashFlowStatement_19eabc62-9742-48db-9773-1dc74704888e" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentTermFollowingDateOfAmendmentPermittedToFinancialAdvisorToConductMeet_ac785885-e426-491f-8364-d944b2f210e0" xlink:href="notv-20240331.xsd#notv_DebtInstrumentTermFollowingDateOfAmendmentPermittedToFinancialAdvisorToConductMeet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentTermFollowingDateOfAmendmentPermittedToFinancialAdvisorToConductMeet_ac785885-e426-491f-8364-d944b2f210e0" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentAdjustmentRate_2c771a1e-965b-4ef2-99e9-60eee8120e5c" xlink:href="notv-20240331.xsd#notv_DebtInstrumentAdjustmentRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentAdjustmentRate_2c771a1e-965b-4ef2-99e9-60eee8120e5c" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentLenderRequirementsAppointedFinancialAdvisorMinimumTerm_5f2f9043-aa33-46de-b0ec-b8925051ae35" xlink:href="notv-20240331.xsd#notv_DebtInstrumentLenderRequirementsAppointedFinancialAdvisorMinimumTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentLenderRequirementsAppointedFinancialAdvisorMinimumTerm_5f2f9043-aa33-46de-b0ec-b8925051ae35" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DomesticCashAndCashEquivalentsOnHandAfterCreditFacilityDraw_752b3abf-7133-4055-be34-352105d6d8fa" xlink:href="notv-20240331.xsd#notv_DomesticCashAndCashEquivalentsOnHandAfterCreditFacilityDraw"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DomesticCashAndCashEquivalentsOnHandAfterCreditFacilityDraw_752b3abf-7133-4055-be34-352105d6d8fa" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentFeePercent_e9690baf-ce50-42bb-8819-55e1ab821d35" xlink:href="notv-20240331.xsd#notv_DebtInstrumentFeePercent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentFeePercent_e9690baf-ce50-42bb-8819-55e1ab821d35" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfOutstandingPrincipalOfTermLoansHeldByConsentingTermLoanLenderPaidInKindAndCapitalized_930e9419-a394-42b2-83ef-85081bf8cb04" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfOutstandingPrincipalOfTermLoansHeldByConsentingTermLoanLenderPaidInKindAndCapitalized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfOutstandingPrincipalOfTermLoansHeldByConsentingTermLoanLenderPaidInKindAndCapitalized_930e9419-a394-42b2-83ef-85081bf8cb04" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfRevolvingCommitmentsHeldByConsentingRevolvingLenderPaidInCashUponCertainPrepayments_135fdd12-5c0c-4f6a-a376-73d75613c4cb" xlink:href="notv-20240331.xsd#notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfRevolvingCommitmentsHeldByConsentingRevolvingLenderPaidInCashUponCertainPrepayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_LineOfCreditFacilityFeeConsiderationPayablePercentageOfRevolvingCommitmentsHeldByConsentingRevolvingLenderPaidInCashUponCertainPrepayments_135fdd12-5c0c-4f6a-a376-73d75613c4cb" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_cbb6ccdf-b803-4918-b048-0c22c4063ec3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_cbb6ccdf-b803-4918-b048-0c22c4063ec3" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_c379dfe6-5bf4-48bb-b0fc-1d80960c208a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_c379dfe6-5bf4-48bb-b0fc-1d80960c208a" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_0e62ecbd-4023-45b6-abd3-c96b6965c6d3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentFairValue_0e62ecbd-4023-45b6-abd3-c96b6965c6d3" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_BusinessCombinationPeriodForPaymentOfConsideration_1ec024dc-f802-4711-9775-84c580ab4b66" xlink:href="notv-20240331.xsd#notv_BusinessCombinationPeriodForPaymentOfConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_BusinessCombinationPeriodForPaymentOfConsideration_1ec024dc-f802-4711-9775-84c580ab4b66" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentSettlementTerm_6b6d0e85-08bf-461d-b274-47eadbcfb0ee" xlink:href="notv-20240331.xsd#notv_DebtInstrumentSettlementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentSettlementTerm_6b6d0e85-08bf-461d-b274-47eadbcfb0ee" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentAdditionalPrincipalAmountIssued_c0c3efe9-7130-4b41-9093-f685e0d84587" xlink:href="notv-20240331.xsd#notv_DebtInstrumentAdditionalPrincipalAmountIssued"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentAdditionalPrincipalAmountIssued_c0c3efe9-7130-4b41-9093-f685e0d84587" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_95e05a20-e7d1-492d-a3ab-92b5e4104599" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionRatio1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionRatio1_95e05a20-e7d1-492d-a3ab-92b5e4104599" xlink:type="arc" order="29"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_20c50e2e-2daa-4c3d-a6ab-ca943d530e55" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleConversionPrice1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleConversionPrice1_20c50e2e-2daa-4c3d-a6ab-ca943d530e55" xlink:type="arc" order="30"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_UnamortizedDebtIssuanceCostsForConvertibleSeniorNotes_93b690b0-768e-4435-a7d5-7b8ff9d94a3c" xlink:href="notv-20240331.xsd#notv_UnamortizedDebtIssuanceCostsForConvertibleSeniorNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_UnamortizedDebtIssuanceCostsForConvertibleSeniorNotes_93b690b0-768e-4435-a7d5-7b8ff9d94a3c" xlink:type="arc" order="31"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseDebt_d419df96-9582-404f-ac31-404f6a2b2790" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_InterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_InterestExpenseDebt_d419df96-9582-404f-ac31-404f6a2b2790" xlink:type="arc" order="32"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_CouponInterestExpenseDebt_458b155b-6e96-4ed4-b3d9-2de11abffeb0" xlink:href="notv-20240331.xsd#notv_CouponInterestExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_CouponInterestExpenseDebt_458b155b-6e96-4ed4-b3d9-2de11abffeb0" xlink:type="arc" order="33"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_AccretionExpenseDebt_476b0c23-c320-48c9-83d8-bc89df10ed0a" xlink:href="notv-20240331.xsd#notv_AccretionExpenseDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_AccretionExpenseDebt_476b0c23-c320-48c9-83d8-bc89df10ed0a" xlink:type="arc" order="34"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_127fa58b-72de-490d-afb2-2402ec7f4006" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AmortizationOfFinancingCostsAndDiscounts"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_AmortizationOfFinancingCostsAndDiscounts_127fa58b-72de-490d-afb2-2402ec7f4006" xlink:type="arc" order="35"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentConvertibleScheduledTradingDays_786b697a-f12d-4819-b07c-5c227d89ff81" xlink:href="notv-20240331.xsd#notv_DebtInstrumentConvertibleScheduledTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentConvertibleScheduledTradingDays_786b697a-f12d-4819-b07c-5c227d89ff81" xlink:type="arc" order="36"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_b16255ea-9a3b-414f-baaa-10d9564c8df6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdPercentageOfStockPriceTrigger_b16255ea-9a3b-414f-baaa-10d9564c8df6" xlink:type="arc" order="37"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_0b3e64ed-c8e4-48b2-8ba5-02b525663c97" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdTradingDays"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdTradingDays_0b3e64ed-c8e4-48b2-8ba5-02b525663c97" xlink:type="arc" order="38"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_b3dcc269-d3ed-42d2-bf70-14168b2a4d2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtInstrumentConvertibleThresholdConsecutiveTradingDays1_b3dcc269-d3ed-42d2-bf70-14168b2a4d2f" xlink:type="arc" order="39"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultCurePeriod_93cd1fbe-efa7-4ed1-8a6a-4fa120df4634" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultCurePeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultCurePeriod_93cd1fbe-efa7-4ed1-8a6a-4fa120df4634" xlink:type="arc" order="40"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultCureOrWaiverPeriodAfterNotice_64c5dba8-59c4-4d63-9530-8b77065d25a8" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultCureOrWaiverPeriodAfterNotice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultCureOrWaiverPeriodAfterNotice_64c5dba8-59c4-4d63-9530-8b77065d25a8" xlink:type="arc" order="41"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtDefaultLongtermDebtAmount_5c3b04f2-b240-47f4-934f-d3086ad46351" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtDefaultLongtermDebtAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_us-gaap_DebtDefaultLongtermDebtAmount_5c3b04f2-b240-47f4-934f-d3086ad46351" xlink:type="arc" order="42"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultPeriodForDischargeOrStay_83cc8d15-8030-40d7-b95f-ef72e543e316" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultPeriodForDischargeOrStay"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultPeriodForDischargeOrStay_83cc8d15-8030-40d7-b95f-ef72e543e316" xlink:type="arc" order="43"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultNoticeForMinimumPercentageOfNoteholders_2550e420-f895-4818-98c4-872ff4d0baf1" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultNoticeForMinimumPercentageOfNoteholders"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultNoticeForMinimumPercentageOfNoteholders_2550e420-f895-4818-98c4-872ff4d0baf1" xlink:type="arc" order="44"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumTerm_c48457fe-82ca-4c9f-bd7f-620590ee59bb" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumTerm_c48457fe-82ca-4c9f-bd7f-620590ee59bb" xlink:type="arc" order="45"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumRate_642440cf-7c5b-4a57-80bc-b3adb9137428" xlink:href="notv-20240331.xsd#notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_DebtInstrumentDebtDefaultRightToReceiveSpecialInterestMaximumRate_642440cf-7c5b-4a57-80bc-b3adb9137428" xlink:type="arc" order="46"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ConvertibleDebtFairValueRemeasurementOfEmbeddedDerivative_63e76f5f-acf5-472c-a8d7-81a386bec727" xlink:href="notv-20240331.xsd#notv_ConvertibleDebtFairValueRemeasurementOfEmbeddedDerivative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_ConvertibleDebtFairValueRemeasurementOfEmbeddedDerivative_63e76f5f-acf5-472c-a8d7-81a386bec727" xlink:type="arc" order="47"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_GainLossOnFairValueRemeasurementOfConvertibleSeniorNotes_9b55e5c6-ebf4-464b-a9a8-f8895222bcde" xlink:href="notv-20240331.xsd#notv_GainLossOnFairValueRemeasurementOfConvertibleSeniorNotes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_GainLossOnFairValueRemeasurementOfConvertibleSeniorNotes_9b55e5c6-ebf4-464b-a9a8-f8895222bcde" xlink:type="arc" order="48"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDebt_7daf7387-de8f-4762-89ab-748886e5ff08" xlink:href="notv-20240331.xsd#notv_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_8748b514-a407-44ed-9616-f8187277a04f" xlink:to="loc_notv_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentLongTermDebt_7daf7387-de8f-4762-89ab-748886e5ff08" xlink:type="arc" order="49"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/DEBTScheduleofEffectiveInterestRatesDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#DEBTScheduleofEffectiveInterestRatesDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/DEBTScheduleofEffectiveInterestRatesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_d7b188dc-5b45-44a8-8233-e9b03c86be26" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_d77b9b3a-cbbf-44ce-848c-f88ecee8179e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d7b188dc-5b45-44a8-8233-e9b03c86be26" xlink:to="loc_us-gaap_DebtInstrumentTable_d77b9b3a-cbbf-44ce-848c-f88ecee8179e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_6ed92880-8b61-42d3-844a-82abfff6144f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_d77b9b3a-cbbf-44ce-848c-f88ecee8179e" xlink:to="loc_us-gaap_CreditFacilityAxis_6ed92880-8b61-42d3-844a-82abfff6144f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_6ed92880-8b61-42d3-844a-82abfff6144f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_6ed92880-8b61-42d3-844a-82abfff6144f" xlink:to="loc_us-gaap_CreditFacilityDomain_6ed92880-8b61-42d3-844a-82abfff6144f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_092ed1b5-f6f6-4000-b35b-8f24f851f8a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_6ed92880-8b61-42d3-844a-82abfff6144f" xlink:to="loc_us-gaap_CreditFacilityDomain_092ed1b5-f6f6-4000-b35b-8f24f851f8a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_TermLoanMember_c286ffa3-37b3-44e5-acbb-2b52df92636f" xlink:href="notv-20240331.xsd#notv_TermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_092ed1b5-f6f6-4000-b35b-8f24f851f8a2" xlink:to="loc_notv_TermLoanMember_c286ffa3-37b3-44e5-acbb-2b52df92636f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DelayedDrawTermLoanMember_75bb7044-3e61-4739-b512-f87328c0d04f" xlink:href="notv-20240331.xsd#notv_DelayedDrawTermLoanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_092ed1b5-f6f6-4000-b35b-8f24f851f8a2" xlink:to="loc_notv_DelayedDrawTermLoanMember_75bb7044-3e61-4739-b512-f87328c0d04f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_AdditionalTermLoansMember_af07368f-30b4-4ccf-ad98-a02e0ccab998" xlink:href="notv-20240331.xsd#notv_AdditionalTermLoansMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_092ed1b5-f6f6-4000-b35b-8f24f851f8a2" xlink:to="loc_notv_AdditionalTermLoansMember_af07368f-30b4-4ccf-ad98-a02e0ccab998" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_7ca714ec-be44-4384-a0fd-175c7b7d5828" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DebtInstrumentInterestRateDuringPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_d7b188dc-5b45-44a8-8233-e9b03c86be26" xlink:to="loc_us-gaap_DebtInstrumentInterestRateDuringPeriod_7ca714ec-be44-4384-a0fd-175c7b7d5828" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/RESTRUCTURINGANDASSETSHELDFORSALENarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#RESTRUCTURINGANDASSETSHELDFORSALENarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/RESTRUCTURINGANDASSETSHELDFORSALENarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanAxis_9fa384ae-d8c9-4efb-a1a2-c647289eade9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_us-gaap_RestructuringPlanAxis_9fa384ae-d8c9-4efb-a1a2-c647289eade9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_9fa384ae-d8c9-4efb-a1a2-c647289eade9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringPlanAxis_9fa384ae-d8c9-4efb-a1a2-c647289eade9" xlink:to="loc_us-gaap_RestructuringPlanDomain_9fa384ae-d8c9-4efb-a1a2-c647289eade9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringPlanDomain_ff9d85a4-5b47-4737-a17d-bc2ad98e2bf5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringPlanDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringPlanAxis_9fa384ae-d8c9-4efb-a1a2-c647289eade9" xlink:to="loc_us-gaap_RestructuringPlanDomain_ff9d85a4-5b47-4737-a17d-bc2ad98e2bf5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_SiteOptimizationPlanMember_b22fb293-8da4-4f5e-bdfc-1138ca5407b8" xlink:href="notv-20240331.xsd#notv_SiteOptimizationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringPlanDomain_ff9d85a4-5b47-4737-a17d-bc2ad98e2bf5" xlink:to="loc_notv_SiteOptimizationPlanMember_b22fb293-8da4-4f5e-bdfc-1138ca5407b8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_f791c6a1-9ca5-472a-b485-e49614e8bb6a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_f791c6a1-9ca5-472a-b485-e49614e8bb6a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_f791c6a1-9ca5-472a-b485-e49614e8bb6a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f791c6a1-9ca5-472a-b485-e49614e8bb6a" xlink:to="loc_us-gaap_SegmentDomain_f791c6a1-9ca5-472a-b485-e49614e8bb6a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_bb25449c-830e-42c3-98e4-23ebbf40ea16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_f791c6a1-9ca5-472a-b485-e49614e8bb6a" xlink:to="loc_us-gaap_SegmentDomain_bb25449c-830e-42c3-98e4-23ebbf40ea16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_ResearchModelsAndServicesSegmentMember_9c2b421f-7c46-4c19-9070-6f91e217ea02" xlink:href="notv-20240331.xsd#notv_ResearchModelsAndServicesSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_bb25449c-830e-42c3-98e4-23ebbf40ea16" xlink:to="loc_notv_ResearchModelsAndServicesSegmentMember_9c2b421f-7c46-4c19-9070-6f91e217ea02" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationAxis_6787f5a7-5afb-4eb5-b440-7788ecdda6ec" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_us-gaap_DisposalGroupClassificationAxis_6787f5a7-5afb-4eb5-b440-7788ecdda6ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_6787f5a7-5afb-4eb5-b440-7788ecdda6ec_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_6787f5a7-5afb-4eb5-b440-7788ecdda6ec" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_6787f5a7-5afb-4eb5-b440-7788ecdda6ec_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupClassificationDomain_edd8d10d-95c2-45d0-9dbb-a487edacc0f7" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupClassificationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DisposalGroupClassificationAxis_6787f5a7-5afb-4eb5-b440-7788ecdda6ec" xlink:to="loc_us-gaap_DisposalGroupClassificationDomain_edd8d10d-95c2-45d0-9dbb-a487edacc0f7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_675c1cea-f55b-4780-8154-4c68f5b3cf57" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DiscontinuedOperationsHeldforsaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_edd8d10d-95c2-45d0-9dbb-a487edacc0f7" xlink:to="loc_us-gaap_DiscontinuedOperationsHeldforsaleMember_675c1cea-f55b-4780-8154-4c68f5b3cf57" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_c853c7b7-28b5-42a0-a402-12d33a0acdef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DiscontinuedOperationsDisposedOfBySaleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupClassificationDomain_edd8d10d-95c2-45d0-9dbb-a487edacc0f7" xlink:to="loc_us-gaap_DiscontinuedOperationsDisposedOfBySaleMember_c853c7b7-28b5-42a0-a402-12d33a0acdef" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9d1b3f8c-e68b-408f-aa82-eac13d55d811" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9d1b3f8c-e68b-408f-aa82-eac13d55d811" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9d1b3f8c-e68b-408f-aa82-eac13d55d811_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9d1b3f8c-e68b-408f-aa82-eac13d55d811" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_9d1b3f8c-e68b-408f-aa82-eac13d55d811_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e3f9cb5a-8f17-4127-8166-cb18e409d51f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperationsAxis_9d1b3f8c-e68b-408f-aa82-eac13d55d811" xlink:to="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e3f9cb5a-8f17-4127-8166-cb18e409d51f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_IsraelRmsAndIsraelCrsBusinessesMember_9dba89ca-4916-4e05-b132-9bdc48ae404b" xlink:href="notv-20240331.xsd#notv_IsraelRmsAndIsraelCrsBusinessesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisposalGroupsIncludingDiscontinuedOperationsNameDomain_e3f9cb5a-8f17-4127-8166-cb18e409d51f" xlink:to="loc_notv_IsraelRmsAndIsraelCrsBusinessesMember_9dba89ca-4916-4e05-b132-9bdc48ae404b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_LegalEntityAxis_ac145ee5-b076-422c-bb76-5317f684459c" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_LegalEntityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_dei_LegalEntityAxis_ac145ee5-b076-422c-bb76-5317f684459c" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_ac145ee5-b076-422c-bb76-5317f684459c_default" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_dei_LegalEntityAxis_ac145ee5-b076-422c-bb76-5317f684459c" xlink:to="loc_dei_EntityDomain_ac145ee5-b076-422c-bb76-5317f684459c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_dei_EntityDomain_735a5e28-b39f-4511-a2d7-f715686ccacc" xlink:href="https://xbrl.sec.gov/dei/2023/dei-2023.xsd#dei_EntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_dei_LegalEntityAxis_ac145ee5-b076-422c-bb76-5317f684459c" xlink:to="loc_dei_EntityDomain_735a5e28-b39f-4511-a2d7-f715686ccacc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_IsraelRmsMember_4a901332-d227-4109-8016-61bddb8987ac" xlink:href="notv-20240331.xsd#notv_IsraelRmsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_dei_EntityDomain_735a5e28-b39f-4511-a2d7-f715686ccacc" xlink:to="loc_notv_IsraelRmsMember_4a901332-d227-4109-8016-61bddb8987ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipAxis_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_63e221e6-4d5d-4368-8f7e-1f2d1e59b068" xlink:to="loc_srt_OwnershipAxis_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_OwnershipAxis_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3" xlink:to="loc_srt_OwnershipDomain_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_OwnershipDomain_ee8e5204-bee0-491a-8fbd-e86683c48ad1" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_OwnershipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_OwnershipAxis_5cbbe4e7-06f8-4952-8d7f-524e2b6baea3" xlink:to="loc_srt_OwnershipDomain_ee8e5204-bee0-491a-8fbd-e86683c48ad1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_IsraelCRSMember_e28be4cf-e072-4894-aae5-ee1d5dcfa9c5" xlink:href="notv-20240331.xsd#notv_IsraelCRSMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_OwnershipDomain_ee8e5204-bee0-491a-8fbd-e86683c48ad1" xlink:to="loc_notv_IsraelCRSMember_e28be4cf-e072-4894-aae5-ee1d5dcfa9c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserve_1d9936b5-5845-4396-8a2a-c1f1946abb53" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RestructuringReserve"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_RestructuringReserve_1d9936b5-5845-4396-8a2a-c1f1946abb53" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetImpairmentCharges_9243e059-47bb-4564-ab2d-2ae6df8c1608" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AssetImpairmentCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_AssetImpairmentCharges_9243e059-47bb-4564-ab2d-2ae6df8c1608" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_a739549d-6ba3-4afe-9d4f-98cdcb9df6b5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration_a739549d-6ba3-4afe-9d4f-98cdcb9df6b5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_58dee62a-f0ef-439b-88a6-f17f2c2140c9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_DiscontinuedOperationIncomeLossFromDiscontinuedOperationBeforeIncomeTax_58dee62a-f0ef-439b-88a6-f17f2c2140c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCash_ceb8394a-43f3-4948-aca0-5e0f20a463f5" xlink:href="notv-20240331.xsd#notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCash_ceb8394a-43f3-4948-aca0-5e0f20a463f5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCashAdjustment_41e71c2f-d606-42eb-99e4-ac2e19547212" xlink:href="notv-20240331.xsd#notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCashAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationCashAdjustment_41e71c2f-d606-42eb-99e4-ac2e19547212" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationRealProperty_2cde7cf7-b0a0-4668-8a00-b49859303a2f" xlink:href="notv-20240331.xsd#notv_DisposalGroupIncludingDiscontinuedOperationConsiderationRealProperty"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationRealProperty_2cde7cf7-b0a0-4668-8a00-b49859303a2f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationPromissoryNoteReceivable_c60d4fb9-450c-4632-aedd-f484094761f7" xlink:href="notv-20240331.xsd#notv_DisposalGroupIncludingDiscontinuedOperationConsiderationPromissoryNoteReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_DisposalGroupIncludingDiscontinuedOperationConsiderationPromissoryNoteReceivable_c60d4fb9-450c-4632-aedd-f484094761f7" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DisposalGroupIncludingDiscontinuedOperationNoteReceivableStatedInterestRate_2877401a-468b-4208-b0af-8e15e8e3cd5e" xlink:href="notv-20240331.xsd#notv_DisposalGroupIncludingDiscontinuedOperationNoteReceivableStatedInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_DisposalGroupIncludingDiscontinuedOperationNoteReceivableStatedInterestRate_2877401a-468b-4208-b0af-8e15e8e3cd5e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_PercentageOfInterestSold_2c855ee1-6f22-4b12-8678-f56f1b231d8b" xlink:href="notv-20240331.xsd#notv_PercentageOfInterestSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_notv_PercentageOfInterestSold_2c855ee1-6f22-4b12-8678-f56f1b231d8b" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_6633dee5-37f0-403e-83fc-60c357665f8c" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_960bbdba-f507-474c-93b0-d06367ba81c1" xlink:to="loc_us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners_6633dee5-37f0-403e-83fc-60c357665f8c" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/LEASESNarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#LEASESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/LEASESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeLeaseDescriptionTable_cbb8f5b6-f212-4ce2-8173-cf7256dafca5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeLeaseDescriptionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:to="loc_us-gaap_LesseeLeaseDescriptionTable_cbb8f5b6-f212-4ce2-8173-cf7256dafca5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a3cd501d-c33f-4fbb-9240-df11ef0468d9" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_cbb8f5b6-f212-4ce2-8173-cf7256dafca5" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a3cd501d-c33f-4fbb-9240-df11ef0468d9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a3cd501d-c33f-4fbb-9240-df11ef0468d9_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a3cd501d-c33f-4fbb-9240-df11ef0468d9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_a3cd501d-c33f-4fbb-9240-df11ef0468d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_44e17c0b-e342-487c-a523-5a1ae047b03f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_a3cd501d-c33f-4fbb-9240-df11ef0468d9" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_44e17c0b-e342-487c-a523-5a1ae047b03f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_FacilitiesLeasedAssetsMember_89d4c6a2-e0bb-4fef-8c8c-3eb33c14d844" xlink:href="notv-20240331.xsd#notv_FacilitiesLeasedAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_44e17c0b-e342-487c-a523-5a1ae047b03f" xlink:to="loc_notv_FacilitiesLeasedAssetsMember_89d4c6a2-e0bb-4fef-8c8c-3eb33c14d844" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_EquipmentLeasedAssetsMember_a4be6c9e-49f8-437f-ab4b-5d0ebf437305" xlink:href="notv-20240331.xsd#notv_EquipmentLeasedAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_44e17c0b-e342-487c-a523-5a1ae047b03f" xlink:to="loc_notv_EquipmentLeasedAssetsMember_a4be6c9e-49f8-437f-ab4b-5d0ebf437305" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_9002b6ee-709f-46cb-902f-33eeb44da0d9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LesseeLeaseDescriptionTable_cbb8f5b6-f212-4ce2-8173-cf7256dafca5" xlink:to="loc_srt_RangeAxis_9002b6ee-709f-46cb-902f-33eeb44da0d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_9002b6ee-709f-46cb-902f-33eeb44da0d9_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_9002b6ee-709f-46cb-902f-33eeb44da0d9" xlink:to="loc_srt_RangeMember_9002b6ee-709f-46cb-902f-33eeb44da0d9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_92b867a8-4ae1-4b3e-a2c6-d0b0cbcabba9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_9002b6ee-709f-46cb-902f-33eeb44da0d9" xlink:to="loc_srt_RangeMember_92b867a8-4ae1-4b3e-a2c6-d0b0cbcabba9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_112b972d-7b6d-4178-a830-b7ceed48f2e8" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_92b867a8-4ae1-4b3e-a2c6-d0b0cbcabba9" xlink:to="loc_srt_MinimumMember_112b972d-7b6d-4178-a830-b7ceed48f2e8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_01ccd88c-716a-4ad2-8b14-dcd9c21d0a5a" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_92b867a8-4ae1-4b3e-a2c6-d0b0cbcabba9" xlink:to="loc_srt_MaximumMember_01ccd88c-716a-4ad2-8b14-dcd9c21d0a5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeOperatingLeaseTermOfContract_c356a1c9-ab76-4875-9198-ebee360d10ca" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:to="loc_us-gaap_LesseeOperatingLeaseTermOfContract_c356a1c9-ab76-4875-9198-ebee360d10ca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LesseeFinanceLeaseTermOfContract1_8c567960-62db-44aa-b821-e0f46d321f5a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LesseeFinanceLeaseTermOfContract1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:to="loc_us-gaap_LesseeFinanceLeaseTermOfContract1_8c567960-62db-44aa-b821-e0f46d321f5a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_68100478-143e-4114-9d94-ad89cb1fc8eb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:to="loc_us-gaap_OperatingLeaseRightOfUseAssetAmortizationExpense_68100478-143e-4114-9d94-ad89cb1fc8eb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_NumberOfFacilitiesCompanyServesAsLessorToLessee_f2c0d64b-5128-4c74-b702-4bca5aa0fb58" xlink:href="notv-20240331.xsd#notv_NumberOfFacilitiesCompanyServesAsLessorToLessee"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LesseeLeaseDescriptionLineItems_08d53340-2fbc-4cca-8781-999ae04db3c0" xlink:to="loc_notv_NumberOfFacilitiesCompanyServesAsLessorToLessee_f2c0d64b-5128-4c74-b702-4bca5aa0fb58" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/EQUITYSTOCKBASEDCOMPENSATIONANDEARNINGSLOSSPERSHARENarrativeDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#EQUITYSTOCKBASEDCOMPENSATIONANDEARNINGSLOSSPERSHARENarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/EQUITYSTOCKBASEDCOMPENSATIONANDEARNINGSLOSSPERSHARENarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ClassOfStockLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfStockByClassTable_2cdadee1-5421-47c6-84d7-0766dc1e43ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ScheduleOfStockByClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_ScheduleOfStockByClassTable_2cdadee1-5421-47c6-84d7-0766dc1e43ef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_4aa581a3-434e-43e5-908d-189133888d16" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_2cdadee1-5421-47c6-84d7-0766dc1e43ef" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_4aa581a3-434e-43e5-908d-189133888d16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4aa581a3-434e-43e5-908d-189133888d16_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4aa581a3-434e-43e5-908d-189133888d16" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4aa581a3-434e-43e5-908d-189133888d16_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ac6067e-5151-40b1-8c08-0296c7df8906" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_4aa581a3-434e-43e5-908d-189133888d16" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ac6067e-5151-40b1-8c08-0296c7df8906" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_EnvigoRmsHoldingCorporationMember_cc006571-e4b8-479f-b562-c534b773013c" xlink:href="notv-20240331.xsd#notv_EnvigoRmsHoldingCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_4ac6067e-5151-40b1-8c08-0296c7df8906" xlink:to="loc_notv_EnvigoRmsHoldingCorporationMember_cc006571-e4b8-479f-b562-c534b773013c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_e2a27d85-321a-47bd-8e29-5252855b4e2f" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfStockByClassTable_2cdadee1-5421-47c6-84d7-0766dc1e43ef" xlink:to="loc_us-gaap_PlanNameAxis_e2a27d85-321a-47bd-8e29-5252855b4e2f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_e2a27d85-321a-47bd-8e29-5252855b4e2f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_e2a27d85-321a-47bd-8e29-5252855b4e2f" xlink:to="loc_us-gaap_PlanNameDomain_e2a27d85-321a-47bd-8e29-5252855b4e2f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_3c4816c9-af56-466d-8dfe-67c8344d7417" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_e2a27d85-321a-47bd-8e29-5252855b4e2f" xlink:to="loc_us-gaap_PlanNameDomain_3c4816c9-af56-466d-8dfe-67c8344d7417" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_InotivInc.2024EquityIncentivePlanThe2024PlanMember_e67834fa-13b0-4402-abac-a9913682e584" xlink:href="notv-20240331.xsd#notv_InotivInc.2024EquityIncentivePlanThe2024PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_3c4816c9-af56-466d-8dfe-67c8344d7417" xlink:to="loc_notv_InotivInc.2024EquityIncentivePlanThe2024PlanMember_e67834fa-13b0-4402-abac-a9913682e584" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_AmendedAndRestated2018EquityIncentivePlanThe2018PlanMember_74e75cab-eb9e-42a1-b8b5-514270864bdf" xlink:href="notv-20240331.xsd#notv_AmendedAndRestated2018EquityIncentivePlanThe2018PlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_3c4816c9-af56-466d-8dfe-67c8344d7417" xlink:to="loc_notv_AmendedAndRestated2018EquityIncentivePlanThe2018PlanMember_74e75cab-eb9e-42a1-b8b5-514270864bdf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_CommonAndPreferredStockSharesAuthorized_30cc9096-88c9-4d64-9c7d-ef2713b42277" xlink:href="notv-20240331.xsd#notv_CommonAndPreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_notv_CommonAndPreferredStockSharesAuthorized_30cc9096-88c9-4d64-9c7d-ef2713b42277" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesAuthorized_2710bad4-8f5d-46ff-91cd-7411b00828bb" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CommonStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_CommonStockSharesAuthorized_2710bad4-8f5d-46ff-91cd-7411b00828bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PreferredStockSharesAuthorized_39c0bf72-f1ef-48d2-b6b5-68c57f209abc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_PreferredStockSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_PreferredStockSharesAuthorized_39c0bf72-f1ef-48d2-b6b5-68c57f209abc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_15abc71f-2ec0-47da-9c71-fdcf89e931a2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfAdditionalSharesAuthorized_15abc71f-2ec0-47da-9c71-fdcf89e931a2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_d260a618-569c-4a44-9dca-871e7582801a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized_d260a618-569c-4a44-9dca-871e7582801a" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_9ff06d72-63a2-49e5-898d-94a61fdd48bc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_9ff06d72-63a2-49e5-898d-94a61fdd48bc" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_4738ce13-00c7-401e-b7ff-6a134ab27c9a" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_StockIssuedDuringPeriodSharesAcquisitions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesAcquisitions_4738ce13-00c7-401e-b7ff-6a134ab27c9a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_df582140-c84f-47d1-9a3f-56235a1661c5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_df582140-c84f-47d1-9a3f-56235a1661c5" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_PostCombinationExpenseInclusiveOfCash_bd1eef32-6250-4aec-8a99-5f8c364d9b3a" xlink:href="notv-20240331.xsd#notv_PostCombinationExpenseInclusiveOfCash"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ClassOfStockLineItems_718f6367-5cb9-4027-87a4-7fce21959d62" xlink:to="loc_notv_PostCombinationExpenseInclusiveOfCash_bd1eef32-6250-4aec-8a99-5f8c364d9b3a" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/CONTINGENCIESDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#CONTINGENCIESDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/CONTINGENCIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_8955235f-aca6-42e9-8ae8-551a4b749ed5" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_us-gaap_LossContingenciesTable_8955235f-aca6-42e9-8ae8-551a4b749ed5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_84526361-e81c-4562-9cd8-fec19ddcb771" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingenciesByNatureOfContingencyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_8955235f-aca6-42e9-8ae8-551a4b749ed5" xlink:to="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_84526361-e81c-4562-9cd8-fec19ddcb771" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_84526361-e81c-4562-9cd8-fec19ddcb771_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_84526361-e81c-4562-9cd8-fec19ddcb771" xlink:to="loc_us-gaap_LossContingencyNatureDomain_84526361-e81c-4562-9cd8-fec19ddcb771_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNatureDomain_0863a52f-031c-4c72-8db8-654880eb93ea" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LossContingenciesByNatureOfContingencyAxis_84526361-e81c-4562-9cd8-fec19ddcb771" xlink:to="loc_us-gaap_LossContingencyNatureDomain_0863a52f-031c-4c72-8db8-654880eb93ea" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_USDOJAgreementInPrincipleMember_86d93bab-f66e-4ebf-8467-a3e2b64a1d92" xlink:href="notv-20240331.xsd#notv_USDOJAgreementInPrincipleMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingencyNatureDomain_0863a52f-031c-4c72-8db8-654880eb93ea" xlink:to="loc_notv_USDOJAgreementInPrincipleMember_86d93bab-f66e-4ebf-8467-a3e2b64a1d92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_8955235f-aca6-42e9-8ae8-551a4b749ed5" xlink:to="loc_srt_StatementGeographicalAxis_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5_default" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5" xlink:to="loc_srt_SegmentGeographicalDomain_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_072de930-e263-4954-861f-459909eba9e9" xlink:href="https://xbrl.fasb.org/srt/2023/elts/srt-2023.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_ae3f5f24-4b27-4d86-8ce7-43bca167d2c5" xlink:to="loc_srt_SegmentGeographicalDomain_072de930-e263-4954-861f-459909eba9e9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_KH_f881c9d6-3c86-43a5-8268-d5bb9c1bb6c3" xlink:href="https://xbrl.sec.gov/country/2023/country-2023.xsd#country_KH"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_072de930-e263-4954-861f-459909eba9e9" xlink:to="loc_country_KH_f881c9d6-3c86-43a5-8268-d5bb9c1bb6c3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_cbefd3e5-e2e7-4fb7-94f1-84f5684b0389" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyEstimateOfPossibleLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_us-gaap_LossContingencyEstimateOfPossibleLoss_cbefd3e5-e2e7-4fb7-94f1-84f5684b0389" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfQuarterlyInstallments_d1c91a9c-1293-4bf9-8e06-3e0576ef9de1" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfQuarterlyInstallments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_notv_LossContingencyNumberOfQuarterlyInstallments_d1c91a9c-1293-4bf9-8e06-3e0576ef9de1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyAccrualProvision_0c99dc69-33f8-4da3-bac8-1c8e65347dfc" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LossContingencyAccrualProvision"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_us-gaap_LossContingencyAccrualProvision_0c99dc69-33f8-4da3-bac8-1c8e65347dfc" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfGovernmentOfficialsIncluded_3550d713-c7ee-45da-97fd-13db1e026fdf" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfGovernmentOfficialsIncluded"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_notv_LossContingencyNumberOfGovernmentOfficialsIncluded_3550d713-c7ee-45da-97fd-13db1e026fdf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfImports_a37942ca-267f-4cde-a37e-edae9e1016b8" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfImports"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_notv_LossContingencyNumberOfImports_a37942ca-267f-4cde-a37e-edae9e1016b8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_LossContingencyNumberOfGovernmentOfficialsTried_7dd1a8b2-6b84-4d6d-84a0-5c65915805ad" xlink:href="notv-20240331.xsd#notv_LossContingencyNumberOfGovernmentOfficialsTried"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_dd0cd439-3b14-4cb3-af3b-d415e727e9b6" xlink:to="loc_notv_LossContingencyNumberOfGovernmentOfficialsTried_7dd1a8b2-6b84-4d6d-84a0-5c65915805ad" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.inotivco.com/role/SUBSEQUENTEVENTSDetails" xlink:type="simple" xlink:href="notv-20240331.xsd#SUBSEQUENTEVENTSDetails"/>
  <link:definitionLink xlink:role="http://www.inotivco.com/role/SUBSEQUENTEVENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_455857ac-e775-4309-99b3-0940c464fc25" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_0fd827b7-3686-421e-8ec2-1f176dde7a7e" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_455857ac-e775-4309-99b3-0940c464fc25" xlink:to="loc_us-gaap_SubsequentEventTable_0fd827b7-3686-421e-8ec2-1f176dde7a7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_df078781-94c4-4270-8b41-ad41a852ec78" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0fd827b7-3686-421e-8ec2-1f176dde7a7e" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_df078781-94c4-4270-8b41-ad41a852ec78" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_df078781-94c4-4270-8b41-ad41a852ec78_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_df078781-94c4-4270-8b41-ad41a852ec78" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_df078781-94c4-4270-8b41-ad41a852ec78_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_f52fa8ef-578f-4867-b209-a1fc06b60ad3" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_df078781-94c4-4270-8b41-ad41a852ec78" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_f52fa8ef-578f-4867-b209-a1fc06b60ad3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_8651e2df-caa1-4114-8a85-9c34d2f526ef" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_f52fa8ef-578f-4867-b209-a1fc06b60ad3" xlink:to="loc_us-gaap_SubsequentEventMember_8651e2df-caa1-4114-8a85-9c34d2f526ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_193b6550-8399-41a0-980c-01c86aa27607" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_0fd827b7-3686-421e-8ec2-1f176dde7a7e" xlink:to="loc_us-gaap_CreditFacilityAxis_193b6550-8399-41a0-980c-01c86aa27607" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_193b6550-8399-41a0-980c-01c86aa27607_default" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_193b6550-8399-41a0-980c-01c86aa27607" xlink:to="loc_us-gaap_CreditFacilityDomain_193b6550-8399-41a0-980c-01c86aa27607_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_3d617309-de6a-433b-8934-8b894ecea55b" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_193b6550-8399-41a0-980c-01c86aa27607" xlink:to="loc_us-gaap_CreditFacilityDomain_3d617309-de6a-433b-8934-8b894ecea55b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_2c01d3b2-440b-4a5e-b11a-2cdfdeac6054" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_3d617309-de6a-433b-8934-8b894ecea55b" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_2c01d3b2-440b-4a5e-b11a-2cdfdeac6054" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_notv_DebtInstrumentCovenantChargesAddBackAllowance_02930d01-a9d9-4560-85ca-3c70c646c578" xlink:href="notv-20240331.xsd#notv_DebtInstrumentCovenantChargesAddBackAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_455857ac-e775-4309-99b3-0940c464fc25" xlink:to="loc_notv_DebtInstrumentCovenantChargesAddBackAllowance_02930d01-a9d9-4560-85ca-3c70c646c578" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_d7aa7a8d-5bc5-4e84-add7-a8920066c9e2" xlink:href="https://xbrl.fasb.org/us-gaap/2023/elts/us-gaap-2023.xsd#us-gaap_LineOfCreditFacilityCommitmentFeePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_455857ac-e775-4309-99b3-0940c464fc25" xlink:to="loc_us-gaap_LineOfCreditFacilityCommitmentFeePercentage_d7aa7a8d-5bc5-4e84-add7-a8920066c9e2" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
