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

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019cc503-7bac-7dda-ab76-08a1c215739b,g:91314959-d3c7-40d0-83f8-945dc5e2f216-->
<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.anterix.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="simple" xlink:href="atex-20260331.xsd#ConsolidatedStatementsofStockholdersEquity"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/ConsolidatedStatementsofStockholdersEquity" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cc503-7d58-7fb9-802b-91b983a2bf3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019cc503-7d58-7f40-ad7e-4a7a2251c5c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7d58-7fb9-802b-91b983a2bf3d" xlink:to="loc_us-gaap_StatementTable_019cc503-7d58-7f40-ad7e-4a7a2251c5c4" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019cc503-7d58-7005-ba16-be4ecc90746f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019cc503-7d58-7f40-ad7e-4a7a2251c5c4" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019cc503-7d58-7005-ba16-be4ecc90746f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7005-ba16-be4ecc90746f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cc503-7d58-7005-ba16-be4ecc90746f" xlink:to="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7005-ba16-be4ecc90746f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7551-99e5-7a012e1405bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019cc503-7d58-7005-ba16-be4ecc90746f" xlink:to="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7551-99e5-7a012e1405bd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019cc503-7d58-739a-b05a-488aad57b68a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7551-99e5-7a012e1405bd" xlink:to="loc_us-gaap_CommonStockMember_019cc503-7d58-739a-b05a-488aad57b68a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019cc503-7d58-7784-9872-05c0924856c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7551-99e5-7a012e1405bd" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019cc503-7d58-7784-9872-05c0924856c8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019cc503-7d58-7d47-8fb9-c7ab9147b154" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019cc503-7d58-7551-99e5-7a012e1405bd" xlink:to="loc_us-gaap_RetainedEarningsMember_019cc503-7d58-7d47-8fb9-c7ab9147b154" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7d58-7fb9-802b-91b983a2bf3d" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019cc503-7d58-79d4-9da2-e6b0eaad74ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_SharesOutstanding_019cc503-7d58-79d4-9da2-e6b0eaad74ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cc503-7d58-793f-a1c2-ddc26bd0b22d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockholdersEquity_019cc503-7d58-793f-a1c2-ddc26bd0b22d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cc503-7d58-7eb0-8a02-1afec636ad54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019cc503-7d58-7eb0-8a02-1afec636ad54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_019cc503-7d58-7ca2-9f0f-a45f675835f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures_019cc503-7d58-7ca2-9f0f-a45f675835f6" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7d58-7049-89cf-1cb6f3880876" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7d58-7049-89cf-1cb6f3880876" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019cc503-7d58-7b8e-b0c4-1ea988938d56" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019cc503-7d58-7b8e-b0c4-1ea988938d56" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019cc503-7d58-7ba4-aec8-901243685966" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019cc503-7d58-7ba4-aec8-901243685966" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019cc503-7d58-7b63-b538-4245c3cef202" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019cc503-7d58-7b63-b538-4245c3cef202" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019cc503-7d58-7368-9789-460721224f7e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019cc503-7d58-7368-9789-460721224f7e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cc503-7d58-709e-8e5a-3e0288db28cc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019cc503-7d58-709e-8e5a-3e0288db28cc" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cc503-7d58-75d5-9b13-97a773603272" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019cc503-7d58-71ae-817c-b14b1db2aaf0" xlink:to="loc_us-gaap_NetIncomeLoss_019cc503-7d58-75d5-9b13-97a773603272" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesOutstanding_019cc503-7d58-7380-97b6-341d178a8a9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019cc503-7d58-71f9-b012-a1765f14dc3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/NatureofOperationsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#NatureofOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/NatureofOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cf509-ec7f-7b99-a731-6b953869967a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-76b4-92f9-f59516fdefa9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cf509-ec7f-7b99-a731-6b953869967a" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-76b4-92f9-f59516fdefa9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019cf509-ec7f-7717-aa06-b0f4a218e868" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-76b4-92f9-f59516fdefa9" xlink:to="loc_srt_CounterpartyNameAxis_019cf509-ec7f-7717-aa06-b0f4a218e868" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7717-aa06-b0f4a218e868_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019cf509-ec7f-7717-aa06-b0f4a218e868" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7717-aa06-b0f4a218e868_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7ed1-a47c-700371ddab37" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019cf509-ec7f-7717-aa06-b0f4a218e868" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7ed1-a47c-700371ddab37" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_NorthWesternEnergyMember_019d77a2-0597-74bc-97b1-0fae464c8301" xlink:href="atex-20260331.xsd#atex_NorthWesternEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7ed1-a47c-700371ddab37" xlink:to="loc_atex_NorthWesternEnergyMember_019d77a2-0597-74bc-97b1-0fae464c8301" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TexasNewMexicoPowerCompanyMember_019d77a3-0722-78d7-97aa-fd7ccabe66e5" xlink:href="atex-20260331.xsd#atex_TexasNewMexicoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7ed1-a47c-700371ddab37" xlink:to="loc_atex_TexasNewMexicoPowerCompanyMember_019d77a3-0722-78d7-97aa-fd7ccabe66e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CPSEnergyMember_019cf509-ec7f-77ff-92bb-2e999b02e429" xlink:href="atex-20260331.xsd#atex_CPSEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cf509-ec7f-7ed1-a47c-700371ddab37" xlink:to="loc_atex_CPSEnergyMember_019cf509-ec7f-77ff-92bb-2e999b02e429" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cf509-ec7f-7c59-9a3a-7ead420d76e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-76b4-92f9-f59516fdefa9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cf509-ec7f-7c59-9a3a-7ead420d76e0" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cf509-ec7f-7c59-9a3a-7ead420d76e0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cf509-ec7f-7c59-9a3a-7ead420d76e0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cf509-ec7f-7c59-9a3a-7ead420d76e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cf509-ec7f-700b-83f3-0728f801550c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cf509-ec7f-7c59-9a3a-7ead420d76e0" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cf509-ec7f-700b-83f3-0728f801550c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_019cf509-ec7f-78a2-89ae-874db34f4da7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cf509-ec7f-700b-83f3-0728f801550c" xlink:to="loc_us-gaap_LicensingAgreementsMember_019cf509-ec7f-78a2-89ae-874db34f4da7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ea916-21e1-7651-b7be-965118cc17bc" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-76b4-92f9-f59516fdefa9" xlink:to="loc_srt_ProductOrServiceAxis_019ea916-21e1-7651-b7be-965118cc17bc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ea916-21e1-7651-b7be-965118cc17bc_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ea916-21e1-7651-b7be-965118cc17bc" xlink:to="loc_srt_ProductsAndServicesDomain_019ea916-21e1-7651-b7be-965118cc17bc_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ea916-21e1-7fb8-8ad0-570241042985" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ea916-21e1-7651-b7be-965118cc17bc" xlink:to="loc_srt_ProductsAndServicesDomain_019ea916-21e1-7fb8-8ad0-570241042985" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019ea916-500d-7fff-8322-cbb7d3382fc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ea916-21e1-7fb8-8ad0-570241042985" xlink:to="loc_us-gaap_LicenseMember_019ea916-500d-7fff-8322-cbb7d3382fc2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedEstimatedConsideration_019d77a3-3cf0-739b-9863-2eedddeb594f" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedEstimatedConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cf509-ec7f-7b99-a731-6b953869967a" xlink:to="loc_atex_BroadbandLicensesGrantedEstimatedConsideration_019d77a3-3cf0-739b-9863-2eedddeb594f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019ea915-ccce-7d6f-b606-8a4293fb906e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cf509-ec7f-7b99-a731-6b953869967a" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019ea915-ccce-7d6f-b606-8a4293fb906e" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#SummaryofSignificantAccountingPoliciesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/SummaryofSignificantAccountingPoliciesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:href="atex-20260331.xsd#atex_SummaryOfSignificantAccountingPoliciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:href="atex-20260331.xsd#atex_SummaryOfSignificantAccountingPoliciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cc503-7d58-7f66-8a9f-18a2e644f8c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cc503-7d58-7f66-8a9f-18a2e644f8c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cc503-7d58-7f66-8a9f-18a2e644f8c5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cc503-7d58-7f66-8a9f-18a2e644f8c5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cc503-7d58-7f66-8a9f-18a2e644f8c5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cc503-7d58-761c-aaca-106d361d2d52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019cc503-7d58-7f66-8a9f-18a2e644f8c5" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cc503-7d58-761c-aaca-106d361d2d52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_019cc503-7d58-7020-87e2-cb79815042c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019cc503-7d58-761c-aaca-106d361d2d52" xlink:to="loc_us-gaap_SalesRevenueNetMember_019cc503-7d58-7020-87e2-cb79815042c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019cc503-7d58-7156-b4d4-81d8a9f6d63f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_srt_MajorCustomersAxis_019cc503-7d58-7156-b4d4-81d8a9f6d63f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cc503-7d58-7156-b4d4-81d8a9f6d63f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019cc503-7d58-7156-b4d4-81d8a9f6d63f" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cc503-7d58-7156-b4d4-81d8a9f6d63f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019cc503-7d58-709b-a206-9b844fafe22a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019cc503-7d58-7156-b4d4-81d8a9f6d63f" xlink:to="loc_srt_NameOfMajorCustomerDomain_019cc503-7d58-709b-a206-9b844fafe22a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_EachCustomerMember_019cc503-7d58-73fb-a31f-bc03336efe46" xlink:href="atex-20260331.xsd#atex_EachCustomerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019cc503-7d58-709b-a206-9b844fafe22a" xlink:to="loc_atex_EachCustomerMember_019cc503-7d58-73fb-a31f-bc03336efe46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019cc503-7d58-791d-b1bd-53478e8d27f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019cc503-7d58-791d-b1bd-53478e8d27f4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cc503-7d58-791d-b1bd-53478e8d27f4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cc503-7d58-791d-b1bd-53478e8d27f4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cc503-7d58-791d-b1bd-53478e8d27f4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019cc503-7d58-70e8-8ecd-8d2cd3808b7f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019cc503-7d58-791d-b1bd-53478e8d27f4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019cc503-7d58-70e8-8ecd-8d2cd3808b7f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019cc503-7d58-7e70-b02b-ce2b02700d4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019cc503-7d58-70e8-8ecd-8d2cd3808b7f" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019cc503-7d58-7e70-b02b-ce2b02700d4e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cc503-7d58-7af2-a817-eaeec15fac26" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_srt_RangeAxis_019cc503-7d58-7af2-a817-eaeec15fac26" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d58-7af2-a817-eaeec15fac26_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cc503-7d58-7af2-a817-eaeec15fac26" xlink:to="loc_srt_RangeMember_019cc503-7d58-7af2-a817-eaeec15fac26_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d58-72b5-ba3c-d84b0d4217d3" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cc503-7d58-7af2-a817-eaeec15fac26" xlink:to="loc_srt_RangeMember_019cc503-7d58-72b5-ba3c-d84b0d4217d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cc503-7d58-7c7e-b579-1b4240ffaddb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d58-72b5-ba3c-d84b0d4217d3" xlink:to="loc_srt_MinimumMember_019cc503-7d58-7c7e-b579-1b4240ffaddb" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cc503-7d58-7326-b1c0-7a7f84cd1d33" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d58-72b5-ba3c-d84b0d4217d3" xlink:to="loc_srt_MaximumMember_019cc503-7d58-7326-b1c0-7a7f84cd1d33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cc503-7d58-73ed-a941-93d36ef28e4b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_srt_ProductOrServiceAxis_019cc503-7d58-73ed-a941-93d36ef28e4b" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cc503-7d58-73ed-a941-93d36ef28e4b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cc503-7d58-73ed-a941-93d36ef28e4b" xlink:to="loc_srt_ProductsAndServicesDomain_019cc503-7d58-73ed-a941-93d36ef28e4b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76f4-8d56-12574e54c916" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cc503-7d58-73ed-a941-93d36ef28e4b" xlink:to="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76f4-8d56-12574e54c916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdvertisingMember_019cc503-7d58-7836-b57b-ac993c7dbcae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdvertisingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76f4-8d56-12574e54c916" xlink:to="loc_us-gaap_AdvertisingMember_019cc503-7d58-7836-b57b-ac993c7dbcae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019ea926-72b0-7320-b340-600888fd384b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76f4-8d56-12574e54c916" xlink:to="loc_us-gaap_LicenseMember_019ea926-72b0-7320-b340-600888fd384b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7d58-7eeb-9fc7-574298e6cc5e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7d58-7eeb-9fc7-574298e6cc5e" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7eeb-9fc7-574298e6cc5e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d58-7eeb-9fc7-574298e6cc5e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7eeb-9fc7-574298e6cc5e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7d43-b220-76b1e9053eee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d58-7eeb-9fc7-574298e6cc5e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7d43-b220-76b1e9053eee" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d58-7162-9b42-acf347688040" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7d43-b220-76b1e9053eee" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d58-7162-9b42-acf347688040" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_019cc503-7d58-7405-8288-dc555f98f28e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d58-7d43-b220-76b1e9053eee" xlink:to="loc_us-gaap_RestrictedStockMember_019cc503-7d58-7405-8288-dc555f98f28e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateAxis_019cc503-7d58-7d20-98f6-09daa7fe4eda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_us-gaap_AwardDateAxis_019cc503-7d58-7d20-98f6-09daa7fe4eda" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_019cc503-7d58-7d20-98f6-09daa7fe4eda_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardDateAxis_019cc503-7d58-7d20-98f6-09daa7fe4eda" xlink:to="loc_us-gaap_AwardDateDomain_019cc503-7d58-7d20-98f6-09daa7fe4eda_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardDateDomain_019cc503-7d58-7923-8f7c-a8ed23848ab2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardDateDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardDateAxis_019cc503-7d58-7d20-98f6-09daa7fe4eda" xlink:to="loc_us-gaap_AwardDateDomain_019cc503-7d58-7923-8f7c-a8ed23848ab2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_GrantsPriorToJuly2023Member_019cc503-7d58-7199-a28f-39fb4a189117" xlink:href="atex-20260331.xsd#atex_GrantsPriorToJuly2023Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AwardDateDomain_019cc503-7d58-7923-8f7c-a8ed23848ab2" xlink:to="loc_atex_GrantsPriorToJuly2023Member_019cc503-7d58-7199-a28f-39fb4a189117" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e6dff-75ca-74aa-ab00-c9faf76f7b7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesTable_019cc503-7d58-708e-ac30-76e3e60a1316" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e6dff-75ca-74aa-ab00-c9faf76f7b7a" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e6dff-75ca-74aa-ab00-c9faf76f7b7a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e6dff-75ca-74aa-ab00-c9faf76f7b7a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e6dff-75ca-74aa-ab00-c9faf76f7b7a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e6dff-75ca-77b3-aabd-838905c8b5a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019e6dff-75ca-74aa-ab00-c9faf76f7b7a" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e6dff-75ca-77b3-aabd-838905c8b5a2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_019e6dff-75ca-7f8f-95ab-e449c0c3ce18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019e6dff-75ca-77b3-aabd-838905c8b5a2" xlink:to="loc_us-gaap_LicensingAgreementsMember_019e6dff-75ca-7f8f-95ab-e449c0c3ce18" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019cc503-7d58-7cfe-ba2f-74fe616645de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_NumberOfReportableSegments_019cc503-7d58-7cfe-ba2f-74fe616645de" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_019cc503-7d58-7648-8163-8b4e4dbae89f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_NumberOfOperatingSegments_019cc503-7d58-7648-8163-8b4e4dbae89f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ConcentrationRiskThresholdPercentage_019cc503-7d58-70fa-8176-57946064c1be" xlink:href="atex-20260331.xsd#atex_ConcentrationRiskThresholdPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_atex_ConcentrationRiskThresholdPercentage_019cc503-7d58-70fa-8176-57946064c1be" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationLiabilitiesSettled_019cc503-7d58-7cb7-ad23-92176a230f48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligationLiabilitiesSettled"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_AssetRetirementObligationLiabilitiesSettled_019cc503-7d58-7cb7-ad23-92176a230f48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetRetirementObligationRevisionOfEstimate_019cc503-7d58-71eb-b288-6ee39dc9c837" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetRetirementObligationRevisionOfEstimate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_AssetRetirementObligationRevisionOfEstimate_019cc503-7d58-71eb-b288-6ee39dc9c837" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cc503-7d58-7f97-b613-e3944564b001" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cc503-7d58-7f97-b613-e3944564b001" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cc503-7d58-7afc-8a83-2bdcc23fb0b0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cc503-7d58-7afc-8a83-2bdcc23fb0b0" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseHeldForSaleTerm_019ea922-1157-7c5d-a542-49b016bdd5f8" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseHeldForSaleTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_atex_BroadbandLicenseHeldForSaleTerm_019ea922-1157-7c5d-a542-49b016bdd5f8" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesHeldForSale_019ea927-559f-7759-af75-e1b064183f77" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesHeldForSale"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_atex_BroadbandLicensesHeldForSale_019ea927-559f-7759-af75-e1b064183f77" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019cc503-7d58-7475-a55d-ef80578b993d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfLongLivedAssetsHeldForUse"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_ImpairmentOfLongLivedAssetsHeldForUse_019cc503-7d58-7475-a55d-ef80578b993d" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019cc503-7d58-7a2a-9771-9850af1b0366" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019cc503-7d58-7a2a-9771-9850af1b0366" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019cc503-7d58-7155-8af3-471ccd273d24" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019cc503-7d58-7155-8af3-471ccd273d24" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_AcceleratedVestingProvisionChangeInControlPurchasePricePerShare_019cc503-7d58-7160-9660-2a1fffc97361" xlink:href="atex-20260331.xsd#atex_AcceleratedVestingProvisionChangeInControlPurchasePricePerShare"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_atex_AcceleratedVestingProvisionChangeInControlPurchasePricePerShare_019cc503-7d58-7160-9660-2a1fffc97361" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019cc503-7d58-7ff4-8a3f-528f33ea3fc3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod_019cc503-7d58-7ff4-8a3f-528f33ea3fc3" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019cc503-7d58-77d0-8ecc-e89607722562" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1_019cc503-7d58-77d0-8ecc-e89607722562" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7d58-7af7-8820-68bc73d6068c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7d58-7af7-8820-68bc73d6068c" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019cc503-7d58-712f-9938-e97c7b5762e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense_019cc503-7d58-712f-9938-e97c7b5762e7" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019cc503-7d58-77ef-b9ee-114be8959867" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_SummaryOfSignificantAccountingPoliciesLineItems_019cc503-7d58-70f6-8edd-90c9553d582f" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019cc503-7d58-77ef-b9ee-114be8959867" xlink:type="arc" order="17"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#RevenueDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RevenueDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-7e6f-bfb0-58aefe802ce0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d27-9126-b11ee4daf1e6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-7e6f-bfb0-58aefe802ce0" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d27-9126-b11ee4daf1e6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cc503-7d58-76c2-ad95-d218dae4350d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d27-9126-b11ee4daf1e6" xlink:to="loc_srt_ProductOrServiceAxis_019cc503-7d58-76c2-ad95-d218dae4350d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76c2-ad95-d218dae4350d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cc503-7d58-76c2-ad95-d218dae4350d" xlink:to="loc_srt_ProductsAndServicesDomain_019cc503-7d58-76c2-ad95-d218dae4350d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cc503-7d58-7ce9-9f26-b396323a1965" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cc503-7d58-76c2-ad95-d218dae4350d" xlink:to="loc_srt_ProductsAndServicesDomain_019cc503-7d58-7ce9-9f26-b396323a1965" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SpectrumMember_019cc503-7d58-77da-9273-81c745dad78d" xlink:href="atex-20260331.xsd#atex_SpectrumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cc503-7d58-7ce9-9f26-b396323a1965" xlink:to="loc_atex_SpectrumMember_019cc503-7d58-77da-9273-81c745dad78d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019cc503-7d58-7173-9bdd-cb7fe973ee56" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d27-9126-b11ee4daf1e6" xlink:to="loc_srt_CounterpartyNameAxis_019cc503-7d58-7173-9bdd-cb7fe973ee56" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7173-9bdd-cb7fe973ee56_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-7173-9bdd-cb7fe973ee56" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7173-9bdd-cb7fe973ee56_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-7173-9bdd-cb7fe973ee56" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_AmerenCorporationMember_019cf54e-9225-7736-9523-7ac0d2b5e3c1" xlink:href="atex-20260331.xsd#atex_AmerenCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:to="loc_atex_AmerenCorporationMember_019cf54e-9225-7736-9523-7ac0d2b5e3c1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_EvergyMember_019cc503-7d58-7662-b0c5-5e59ca8d0251" xlink:href="atex-20260331.xsd#atex_EvergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:to="loc_atex_EvergyMember_019cc503-7d58-7662-b0c5-5e59ca8d0251" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_XcelEnergyServicesIncMember_019cc503-7d58-7bc0-97f9-3eb26114431e" xlink:href="atex-20260331.xsd#atex_XcelEnergyServicesIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:to="loc_atex_XcelEnergyServicesIncMember_019cc503-7d58-7bc0-97f9-3eb26114431e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TampaElectricCompanyMember_019cf54c-7a48-7232-a5cf-0fcdefe874be" xlink:href="atex-20260331.xsd#atex_TampaElectricCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:to="loc_atex_TampaElectricCompanyMember_019cf54c-7a48-7232-a5cf-0fcdefe874be" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_MotorolaMember_019cc503-7d58-7e38-a21a-5f2de4f4c4cb" xlink:href="atex-20260331.xsd#atex_MotorolaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7b9a-893d-0aeeba9c6cf8" xlink:to="loc_atex_MotorolaMember_019cc503-7d58-7e38-a21a-5f2de4f4c4cb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019cc503-7d58-7c01-b92a-43d68de45567" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-7e6f-bfb0-58aefe802ce0" xlink:to="loc_us-gaap_Revenues_019cc503-7d58-7c01-b92a-43d68de45567" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RevenueSpectrumLeaseAgreementsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#RevenueSpectrumLeaseAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RevenueSpectrumLeaseAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019dd226-9432-7e62-8fec-cb7f91117ad5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019dd226-9432-7e62-8fec-cb7f91117ad5" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019dd226-9432-76c5-8f21-5553ddcd622e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019dd226-9432-7e62-8fec-cb7f91117ad5" xlink:to="loc_srt_CounterpartyNameAxis_019dd226-9432-76c5-8f21-5553ddcd622e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-76c5-8f21-5553ddcd622e_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019dd226-9432-76c5-8f21-5553ddcd622e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-76c5-8f21-5553ddcd622e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019dd226-9432-76c5-8f21-5553ddcd622e" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_AmerenCorporationMember_019dd226-9432-7338-bca9-3bde1c8e023f" xlink:href="atex-20260331.xsd#atex_AmerenCorporationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:to="loc_atex_AmerenCorporationMember_019dd226-9432-7338-bca9-3bde1c8e023f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_EvergyMember_019dd226-9432-79b2-83ef-d1b85b5878a3" xlink:href="atex-20260331.xsd#atex_EvergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:to="loc_atex_EvergyMember_019dd226-9432-79b2-83ef-d1b85b5878a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_XcelEnergyServicesIncMember_019dd226-9432-77e3-9a43-f62a1de8719b" xlink:href="atex-20260331.xsd#atex_XcelEnergyServicesIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:to="loc_atex_XcelEnergyServicesIncMember_019dd226-9432-77e3-9a43-f62a1de8719b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TampaElectricCompanyMember_019dd226-9432-7cc1-bbf8-00b69c6a24fa" xlink:href="atex-20260331.xsd#atex_TampaElectricCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd226-9432-7361-af10-49fdbcd12c65" xlink:to="loc_atex_TampaElectricCompanyMember_019dd226-9432-7cc1-bbf8-00b69c6a24fa" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019e7306-6125-7b6b-b214-76786fb9c212" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019dd226-9432-7e62-8fec-cb7f91117ad5" xlink:to="loc_srt_RangeAxis_019e7306-6125-7b6b-b214-76786fb9c212" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e7306-6125-7b6b-b214-76786fb9c212_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019e7306-6125-7b6b-b214-76786fb9c212" xlink:to="loc_srt_RangeMember_019e7306-6125-7b6b-b214-76786fb9c212_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019e7306-6125-75f3-a46d-1bc8889c247e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019e7306-6125-7b6b-b214-76786fb9c212" xlink:to="loc_srt_RangeMember_019e7306-6125-75f3-a46d-1bc8889c247e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019e7306-dded-7807-9d17-7d50e7156780" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e7306-6125-75f3-a46d-1bc8889c247e" xlink:to="loc_srt_MinimumMember_019e7306-dded-7807-9d17-7d50e7156780" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019e7307-0386-7aa2-8749-4acb5fbd07f5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019e7306-6125-75f3-a46d-1bc8889c247e" xlink:to="loc_srt_MaximumMember_019e7307-0386-7aa2-8749-4acb5fbd07f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeaseTermOfContract_019dd226-d420-7d3a-8cd2-687c785c7855" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeaseTermOfContract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_us-gaap_LessorOperatingLeaseTermOfContract_019dd226-d420-7d3a-8cd2-687c785c7855" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019e7305-d8a9-76cf-a43b-99152d9c1065" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019e7305-d8a9-76cf-a43b-99152d9c1065" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_019dd226-9433-7a3b-abd9-96628f3cfaf8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeasePaymentsToBeReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_us-gaap_LessorOperatingLeasePaymentsToBeReceived_019dd226-9433-7a3b-abd9-96628f3cfaf8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLeaseLeaseIncome_019dd226-9433-7903-8c39-bb441c9155e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLeaseLeaseIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_us-gaap_OperatingLeaseLeaseIncome_019dd226-9433-7903-8c39-bb441c9155e8" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LessorOperatingLeaseRenewalTermNumber_019e827d-6cf5-7a73-8ea6-73f177fac230" xlink:href="atex-20260331.xsd#atex_LessorOperatingLeaseRenewalTermNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_atex_LessorOperatingLeaseRenewalTermNumber_019e827d-6cf5-7a73-8ea6-73f177fac230" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_OperatingLeaseIncomeComprehensiveIncomeExtensibleListNotDisclosedFlag_019ea92e-e533-7cef-bc6c-031c038140c4" xlink:href="atex-20260331.xsd#atex_OperatingLeaseIncomeComprehensiveIncomeExtensibleListNotDisclosedFlag"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019dd226-9433-7094-a738-7e4234050508" xlink:to="loc_atex_OperatingLeaseIncomeComprehensiveIncomeExtensibleListNotDisclosedFlag_019ea92e-e533-7cef-bc6c-031c038140c4" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RevenueSpectrumSaleAgreementsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#RevenueSpectrumSaleAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RevenueSpectrumSaleAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019e4978-637c-7d35-9790-00c98908a552" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019e4978-637c-7d35-9790-00c98908a552" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019e4978-637c-7db8-9f3b-5cf88c946b9c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e4978-637c-7d35-9790-00c98908a552" xlink:to="loc_srt_CounterpartyNameAxis_019e4978-637c-7db8-9f3b-5cf88c946b9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7db8-9f3b-5cf88c946b9c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019e4978-637c-7db8-9f3b-5cf88c946b9c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7db8-9f3b-5cf88c946b9c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7611-a47b-af2fd944dffb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019e4978-637c-7db8-9f3b-5cf88c946b9c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7611-a47b-af2fd944dffb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CPSEnergyMember_019e4978-637c-71f0-934b-5dd809c08279" xlink:href="atex-20260331.xsd#atex_CPSEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7611-a47b-af2fd944dffb" xlink:to="loc_atex_CPSEnergyMember_019e4978-637c-71f0-934b-5dd809c08279" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TexasNewMexicoPowerCompanyMember_019e4978-637c-7c69-b43f-634d92c2f5bb" xlink:href="atex-20260331.xsd#atex_TexasNewMexicoPowerCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7611-a47b-af2fd944dffb" xlink:to="loc_atex_TexasNewMexicoPowerCompanyMember_019e4978-637c-7c69-b43f-634d92c2f5bb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_NorthWesternEnergyMember_019e4978-637c-7030-8d74-74bce43279e9" xlink:href="atex-20260331.xsd#atex_NorthWesternEnergyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e4978-637c-7611-a47b-af2fd944dffb" xlink:to="loc_atex_NorthWesternEnergyMember_019e4978-637c-7030-8d74-74bce43279e9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ea91c-003b-7b70-832d-94d66c7c74af" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019e4978-637c-7d35-9790-00c98908a552" xlink:to="loc_srt_ProductOrServiceAxis_019ea91c-003b-7b70-832d-94d66c7c74af" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ea91c-003b-7b70-832d-94d66c7c74af_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ea91c-003b-7b70-832d-94d66c7c74af" xlink:to="loc_srt_ProductsAndServicesDomain_019ea91c-003b-7b70-832d-94d66c7c74af_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ea91c-003b-7d17-bf46-9e9810e676c5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ea91c-003b-7b70-832d-94d66c7c74af" xlink:to="loc_srt_ProductsAndServicesDomain_019ea91c-003b-7d17-bf46-9e9810e676c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019ea91c-214c-76c4-88ab-46d06ee62320" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ea91c-003b-7d17-bf46-9e9810e676c5" xlink:to="loc_us-gaap_LicenseMember_019ea91c-214c-76c4-88ab-46d06ee62320" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019e4978-637c-7811-af99-a34d49b0b9d0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019e4978-637c-7811-af99-a34d49b0b9d0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019e4978-637c-7459-97b6-3eb6cd93e6f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019e4978-637c-7459-97b6-3eb6cd93e6f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_RevenueRemainingPerformanceObligationPaymentsRemaining_019e4978-637c-7d9e-9a50-24017cd6b0a2" xlink:href="atex-20260331.xsd#atex_RevenueRemainingPerformanceObligationPaymentsRemaining"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:to="loc_atex_RevenueRemainingPerformanceObligationPaymentsRemaining_019e4978-637c-7d9e-9a50-24017cd6b0a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedNumberOfLicenseRemaining_019e4978-637c-7d1c-b98f-519856c7d1bb" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedNumberOfLicenseRemaining"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019e4978-637c-796c-bf02-d25fb11c0afa" xlink:to="loc_atex_BroadbandLicensesGrantedNumberOfLicenseRemaining_019e4978-637c-7d1c-b98f-519856c7d1bb" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RevenueNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#RevenueNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RevenueNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019cc503-7d58-78a5-8f66-084d4dc3eacf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019cc503-7d58-78a5-8f66-084d4dc3eacf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:to="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-71a6-9498-7c6301b2e71d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-71a6-9498-7c6301b2e71d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SpectrumMember_019dcfbf-1375-7e6e-b60e-6073740d8fea" xlink:href="atex-20260331.xsd#atex_SpectrumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:to="loc_atex_SpectrumMember_019dcfbf-1375-7e6e-b60e-6073740d8fea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:to="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:to="loc_srt_RangeMember_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:to="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019dcfbf-1375-7219-aad6-dfef75f90957" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:to="loc_srt_MaximumMember_019dcfbf-1375-7219-aad6-dfef75f90957" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019dcfbf-1375-7917-9b9f-11be97535436" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019dcfbf-1375-7917-9b9f-11be97535436" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_019dcfbf-1375-7d68-908c-61759532318c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_019dcfbf-1375-7d68-908c-61759532318c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019cc503-7d58-7347-b4de-cf8c3645c393" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019cc503-7d58-7347-b4de-cf8c3645c393" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019cc503-7d58-7609-9d47-85269c480f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019cc503-7d58-7609-9d47-85269c480f1d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RevenueNarrativeDetails_1" xlink:type="simple" xlink:href="atex-20260331.xsd#RevenueNarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RevenueNarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:to="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-71a6-9498-7c6301b2e71d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-71a6-9498-7c6301b2e71d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019dcfbf-1375-71a6-9498-7c6301b2e71d" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SpectrumMember_019dcfbf-1375-7e6e-b60e-6073740d8fea" xlink:href="atex-20260331.xsd#atex_SpectrumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019dcfbf-1375-7922-a2a6-d4ece20fc271" xlink:to="loc_atex_SpectrumMember_019dcfbf-1375-7e6e-b60e-6073740d8fea" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019cc503-7d58-7d7b-a80e-dcd8ec2c27d1" xlink:to="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:to="loc_srt_RangeMember_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019dcfbf-1375-7313-a9a7-6d0c4b9ffbfd" xlink:to="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019dcfbf-1375-7219-aad6-dfef75f90957" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019dcfbf-1375-75ae-a9c6-ae98b2d0aa0d" xlink:to="loc_srt_MaximumMember_019dcfbf-1375-7219-aad6-dfef75f90957" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019dcfbf-1375-7917-9b9f-11be97535436" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PrepaidExpenseAndOtherAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_PrepaidExpenseAndOtherAssetsCurrent_019dcfbf-1375-7917-9b9f-11be97535436" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_019dcfbf-1375-7d68-908c-61759532318c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CapitalizedContractCostAmortizationPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_CapitalizedContractCostAmortizationPeriod_019dcfbf-1375-7d68-908c-61759532318c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019cc503-7d58-7347-b4de-cf8c3645c393" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019cc503-7d58-7347-b4de-cf8c3645c393" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019cc503-7d58-7609-9d47-85269c480f1d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019cc503-7d58-75b8-95b1-dbfbaa8e5fe1" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019cc503-7d58-7609-9d47-85269c480f1d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/SegmentReportingReconciliationofRevenuetoNetLossDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#SegmentReportingReconciliationofRevenuetoNetLossDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/SegmentReportingReconciliationofRevenuetoNetLossDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019cc503-7d58-72cb-9cde-82b9c5f8e640" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cc503-7d58-7ac8-9df3-ae2abae60f06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cc503-7d58-72cb-9cde-82b9c5f8e640" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cc503-7d58-7ac8-9df3-ae2abae60f06" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019cc503-7d58-735d-847b-154580f62f30" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019cc503-7d58-7ac8-9df3-ae2abae60f06" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019cc503-7d58-735d-847b-154580f62f30" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cc503-7d58-735d-847b-154580f62f30_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cc503-7d58-735d-847b-154580f62f30" xlink:to="loc_us-gaap_SegmentDomain_019cc503-7d58-735d-847b-154580f62f30_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019cc503-7d58-72e2-857c-260676da28df" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019cc503-7d58-735d-847b-154580f62f30" xlink:to="loc_us-gaap_SegmentDomain_019cc503-7d58-72e2-857c-260676da28df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ReportableSegmentMember_019cc503-7d58-7d04-b7a5-1d729289b574" xlink:href="atex-20260331.xsd#atex_ReportableSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019cc503-7d58-72e2-857c-260676da28df" xlink:to="loc_atex_ReportableSegmentMember_019cc503-7d58-7d04-b7a5-1d729289b574" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Revenues_019cc503-7d58-744c-b226-8578f5c93d8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Revenues"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cc503-7d58-72cb-9cde-82b9c5f8e640" xlink:to="loc_us-gaap_Revenues_019cc503-7d58-744c-b226-8578f5c93d8d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cc503-7d58-72cb-9cde-82b9c5f8e640" xlink:to="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_GeneralAndAdministrativeExpenseAdjusted_019cc503-7d58-715d-a5df-ad385d59ef81" xlink:href="atex-20260331.xsd#atex_GeneralAndAdministrativeExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_atex_GeneralAndAdministrativeExpenseAdjusted_019cc503-7d58-715d-a5df-ad385d59ef81" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SellingAndMarketingExpenseAdjusted_019cc503-7d58-74b7-803f-464d56d4f4bf" xlink:href="atex-20260331.xsd#atex_SellingAndMarketingExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_atex_SellingAndMarketingExpenseAdjusted_019cc503-7d58-74b7-803f-464d56d4f4bf" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ResearchAndDevelopmentExpenseAdjusted_019cc503-7d58-74e0-9d67-9933f8937af1" xlink:href="atex-20260331.xsd#atex_ResearchAndDevelopmentExpenseAdjusted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_atex_ResearchAndDevelopmentExpenseAdjusted_019cc503-7d58-74e0-9d67-9933f8937af1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019cc503-7d58-7444-9d3c-d8a88e3cf8d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019cc503-7d58-7444-9d3c-d8a88e3cf8d7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_GainLossOnExchangeOfIntangibleAssets_019cc503-7d58-7a06-aca2-0290ac08a508" xlink:href="atex-20260331.xsd#atex_GainLossOnExchangeOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_atex_GainLossOnExchangeOfIntangibleAssets_019cc503-7d58-7a06-aca2-0290ac08a508" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_GainOnSaleOfIntangibleAssets_019cc503-7d58-7fec-9a02-8dd17d25ecf2" xlink:href="atex-20260331.xsd#atex_GainOnSaleOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_atex_GainOnSaleOfIntangibleAssets_019cc503-7d58-7fec-9a02-8dd17d25ecf2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestIncomeOther_019cc503-7d58-7006-a7ad-3efbbb693f5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestIncomeOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_us-gaap_InterestIncomeOther_019cc503-7d58-7006-a7ad-3efbbb693f5b" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019cc503-7d58-7d45-ba08-18e7b81293d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019cc503-7d58-7d45-ba08-18e7b81293d9" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019cc503-7d58-7f9d-aee8-f1eb7476690e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019cc503-7d58-7f9d-aee8-f1eb7476690e" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019cc503-7d58-77e3-9446-bb91edccdfd3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ReconciliationFromSegmentTotalsToConsolidatedAbstract_019cc503-7d58-71b9-953c-967c80807389" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019cc503-7d58-77e3-9446-bb91edccdfd3" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019cc503-7d58-747b-9bbe-dd5bbdb3bd95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019cc503-7d58-72cb-9cde-82b9c5f8e640" xlink:to="loc_us-gaap_NetIncomeLoss_019cc503-7d58-747b-9bbe-dd5bbdb3bd95" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/EscrowDepositsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#EscrowDepositsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/EscrowDepositsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-725a-b1c8-9af61138e498" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-725a-b1c8-9af61138e498" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019cc503-7d58-798b-9269-9400ed148ba1" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-725a-b1c8-9af61138e498" xlink:to="loc_srt_CounterpartyNameAxis_019cc503-7d58-798b-9269-9400ed148ba1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-798b-9269-9400ed148ba1_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-798b-9269-9400ed148ba1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-798b-9269-9400ed148ba1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7f0d-b915-12a5154d453f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-798b-9269-9400ed148ba1" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7f0d-b915-12a5154d453f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019cc503-7d58-7524-aec7-5b3262863d06" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityLCRAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7f0d-b915-12a5154d453f" xlink:to="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019cc503-7d58-7524-aec7-5b3262863d06" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_019cc503-7d58-7372-8e3b-4ff16f110430" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-725a-b1c8-9af61138e498" xlink:to="loc_us-gaap_TypeOfArrangementAxis_019cc503-7d58-7372-8e3b-4ff16f110430" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019cc503-7d58-7372-8e3b-4ff16f110430_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019cc503-7d58-7372-8e3b-4ff16f110430" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019cc503-7d58-7372-8e3b-4ff16f110430_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019cc503-7d58-7036-a519-a3c9eb4ea477" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019cc503-7d58-7372-8e3b-4ff16f110430" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019cc503-7d58-7036-a519-a3c9eb4ea477" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember_019cc503-7d58-7572-a964-daeae84d8355" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019cc503-7d58-7036-a519-a3c9eb4ea477" xlink:to="loc_us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember_019cc503-7d58-7572-a964-daeae84d8355" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019cf5ac-20a8-797d-b746-560036301245" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019cc503-7d58-725a-b1c8-9af61138e498" xlink:to="loc_srt_ProductOrServiceAxis_019cf5ac-20a8-797d-b746-560036301245" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cf5ac-20a8-797d-b746-560036301245_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019cf5ac-20a8-797d-b746-560036301245" xlink:to="loc_srt_ProductsAndServicesDomain_019cf5ac-20a8-797d-b746-560036301245_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019cf5ac-20a8-7750-bc3e-6be83af1620e" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019cf5ac-20a8-797d-b746-560036301245" xlink:to="loc_srt_ProductsAndServicesDomain_019cf5ac-20a8-7750-bc3e-6be83af1620e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_WirelessLicensesMember_019cf5ac-20a8-7ea1-ac4c-cbed458ae20b" xlink:href="atex-20260331.xsd#atex_WirelessLicensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019cf5ac-20a8-7750-bc3e-6be83af1620e" xlink:to="loc_atex_WirelessLicensesMember_019cf5ac-20a8-7ea1-ac4c-cbed458ae20b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsInitialPaymentReceived_019cc503-7d58-713f-8412-62be6670fafd" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsInitialPaymentReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsInitialPaymentReceived_019cc503-7d58-713f-8412-62be6670fafd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets_019cc503-7d58-7810-98c9-414548b10262" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInDepositOtherAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_us-gaap_IncreaseDecreaseInDepositOtherAssets_019cc503-7d58-7810-98c9-414548b10262" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_EscrowDepositCurrent_019cc503-7d58-769e-bf4d-16fca8fda194" xlink:href="atex-20260331.xsd#atex_EscrowDepositCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_atex_EscrowDepositCurrent_019cc503-7d58-769e-bf4d-16fca8fda194" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019cf5ac-20a8-7056-b34a-c0789f970471" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019cf5ac-20a8-7056-b34a-c0789f970471" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_EscrowDepositCumulative_019e8df1-3289-7ab7-b614-e554ec343573" xlink:href="atex-20260331.xsd#atex_EscrowDepositCumulative"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019cc503-7d58-74de-a2c2-0f41f0e67d3e" xlink:to="loc_atex_EscrowDepositCumulative_019e8df1-3289-7ab7-b614-e554ec343573" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/PropertyandEquipmentComponentsofPropertyandEquipmentDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#PropertyandEquipmentComponentsofPropertyandEquipmentDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/PropertyandEquipmentComponentsofPropertyandEquipmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cc503-7d58-7e19-9fd7-edc57e664adf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cc503-7d58-7e19-9fd7-edc57e664adf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cc503-7d58-7a79-9cc8-783030a90a10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cc503-7d58-7e19-9fd7-edc57e664adf" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cc503-7d58-7a79-9cc8-783030a90a10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-7a79-9cc8-783030a90a10_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cc503-7d58-7a79-9cc8-783030a90a10" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-7a79-9cc8-783030a90a10_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019cc503-7d58-7a79-9cc8-783030a90a10" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_NetworkSitesAndEquipmentMember_019cc503-7d58-7a87-b233-51efb826d937" xlink:href="atex-20260331.xsd#atex_NetworkSitesAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:to="loc_atex_NetworkSitesAndEquipmentMember_019cc503-7d58-7a87-b233-51efb826d937" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019cc503-7d58-7206-8706-3c86a251123f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SoftwareAndSoftwareDevelopmentCostsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:to="loc_us-gaap_SoftwareAndSoftwareDevelopmentCostsMember_019cc503-7d58-7206-8706-3c86a251123f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComputerEquipmentMember_019cc503-7d58-7f86-bc66-aad30be97417" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComputerEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:to="loc_us-gaap_ComputerEquipmentMember_019cc503-7d58-7f86-bc66-aad30be97417" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FurnitureAndFixturesMember_019cc503-7d58-7061-9cc7-97730c629c98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FurnitureAndFixturesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:to="loc_us-gaap_FurnitureAndFixturesMember_019cc503-7d58-7061-9cc7-97730c629c98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LeaseholdImprovementsMember_019cc503-7d58-743b-8a6e-55234701216e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LeaseholdImprovementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019cc503-7d58-732b-8fd5-52f730383d74" xlink:to="loc_us-gaap_LeaseholdImprovementsMember_019cc503-7d58-743b-8a6e-55234701216e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cc503-7d58-773a-897d-b546de43272b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019cc503-7d58-7e19-9fd7-edc57e664adf" xlink:to="loc_srt_RangeAxis_019cc503-7d58-773a-897d-b546de43272b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d58-773a-897d-b546de43272b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cc503-7d58-773a-897d-b546de43272b" xlink:to="loc_srt_RangeMember_019cc503-7d58-773a-897d-b546de43272b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d58-7556-b4bf-127f49a298d8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cc503-7d58-773a-897d-b546de43272b" xlink:to="loc_srt_RangeMember_019cc503-7d58-7556-b4bf-127f49a298d8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cc503-7d58-73e0-ad43-55289fa2286c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d58-7556-b4bf-127f49a298d8" xlink:to="loc_srt_MinimumMember_019cc503-7d58-73e0-ad43-55289fa2286c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cc503-7d58-776f-86f3-84b37dd21c42" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d58-7556-b4bf-127f49a298d8" xlink:to="loc_srt_MaximumMember_019cc503-7d58-776f-86f3-84b37dd21c42" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019cc503-7d58-7fc6-aef0-72b6ff14ad4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentUsefulLife_019cc503-7d58-7fc6-aef0-72b6ff14ad4a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019cc503-7d58-7a27-a100-ec0f73f9e8a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019cc503-7d58-7a27-a100-ec0f73f9e8a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019cc503-7d58-7b55-9c4c-d8adab83296e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:to="loc_us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment_019cc503-7d58-7b55-9c4c-d8adab83296e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentNet_019cc503-7d58-7853-a179-1992c328389b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019cc503-7d58-768d-9a8d-f6e5294c1dda" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentNet_019cc503-7d58-7853-a179-1992c328389b" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/IntangibleAssetsNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#IntangibleAssetsNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/IntangibleAssetsNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019cc503-7d58-7ce9-8eec-7cfb739da7ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019cc503-7d58-7ce9-8eec-7cfb739da7ce" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cc503-7d58-79fb-a115-822a46f03c20" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019cc503-7d58-7ce9-8eec-7cfb739da7ce" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cc503-7d58-79fb-a115-822a46f03c20" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cc503-7d58-79fb-a115-822a46f03c20_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cc503-7d58-79fb-a115-822a46f03c20" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cc503-7d58-79fb-a115-822a46f03c20_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cc503-7d58-7989-9a32-90cff9860af6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019cc503-7d58-79fb-a115-822a46f03c20" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cc503-7d58-7989-9a32-90cff9860af6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_019cc503-7d58-7048-b8bc-a771659f2a1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019cc503-7d58-7989-9a32-90cff9860af6" xlink:to="loc_us-gaap_LicensingAgreementsMember_019cc503-7d58-7048-b8bc-a771659f2a1c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019cc503-7d58-7907-a6e2-1352947c754a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAcquiredIndefiniteLivedIntangibleAssetsByMajorClassTable_019cc503-7d58-7ce9-8eec-7cfb739da7ce" xlink:to="loc_srt_CounterpartyNameAxis_019cc503-7d58-7907-a6e2-1352947c754a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7907-a6e2-1352947c754a_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-7907-a6e2-1352947c754a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7907-a6e2-1352947c754a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7316-b929-f1357d0ccec4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019cc503-7d58-7907-a6e2-1352947c754a" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7316-b929-f1357d0ccec4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityMember_019cf5bb-dfba-792c-9497-9e474116187a" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7316-b929-f1357d0ccec4" xlink:to="loc_atex_LowerColoradoRiverAuthorityMember_019cf5bb-dfba-792c-9497-9e474116187a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_OncorElectricDeliveryCompanyLLCMember_019cc503-7d58-77f4-be3c-763ac760f824" xlink:href="atex-20260331.xsd#atex_OncorElectricDeliveryCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019cc503-7d58-7316-b929-f1357d0ccec4" xlink:to="loc_atex_OncorElectricDeliveryCompanyLLCMember_019cc503-7d58-77f4-be3c-763ac760f824" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cc503-7d58-73b3-9175-7ee4069fa6e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_us-gaap_ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill_019cc503-7d58-73b3-9175-7ee4069fa6e1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedNumberOfCounties_019cc503-7d58-7e26-b473-f734aca892c4" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedNumberOfCounties"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_BroadbandLicensesGrantedNumberOfCounties_019cc503-7d58-7e26-b473-f734aca892c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_IndefinitelivedIntangibleAssetsExchangedLicensesReceived_019cc503-7d58-7924-9507-d1dfc2a28591" xlink:href="atex-20260331.xsd#atex_IndefinitelivedIntangibleAssetsExchangedLicensesReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_IndefinitelivedIntangibleAssetsExchangedLicensesReceived_019cc503-7d58-7924-9507-d1dfc2a28591" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_IndefinitelivedIntangibleAssetsExchangedLicensesSurrendered_019cc503-7d58-747e-adc1-cff41c594c75" xlink:href="atex-20260331.xsd#atex_IndefinitelivedIntangibleAssetsExchangedLicensesSurrendered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_IndefinitelivedIntangibleAssetsExchangedLicensesSurrendered_019cc503-7d58-747e-adc1-cff41c594c75" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesTransferredTotalConsideration_019cc503-7d58-72bf-ae1f-d8263e6a6456" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesTransferredTotalConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_BroadbandLicensesTransferredTotalConsideration_019cc503-7d58-72bf-ae1f-d8263e6a6456" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireIntangibleAssets_019cc503-7d58-7a7b-92f8-c318e715399d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_us-gaap_PaymentsToAcquireIntangibleAssets_019cc503-7d58-7a7b-92f8-c318e715399d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019cf5bb-dfba-7d7a-a751-e08f6003b357" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1_019cf5bb-dfba-7d7a-a751-e08f6003b357" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsPeriodIncreaseDecrease_019cc503-7d58-7a1e-9f31-ae7b025850d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsPeriodIncreaseDecrease"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsPeriodIncreaseDecrease_019cc503-7d58-7a1e-9f31-ae7b025850d4" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseSaleAssetsAllocatedFromPreviouslyReceivedAmount_019cc503-7d58-75c8-b3b2-643c47058990" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseSaleAssetsAllocatedFromPreviouslyReceivedAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_BroadbandLicenseSaleAssetsAllocatedFromPreviouslyReceivedAmount_019cc503-7d58-75c8-b3b2-643c47058990" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseSaleDeposit_019cc503-7d58-7884-9591-6c23e19728a8" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseSaleDeposit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_BroadbandLicenseSaleDeposit_019cc503-7d58-7884-9591-6c23e19728a8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments_019cc503-7d58-7ea1-98dd-2a4c47dbbaef" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments_019cc503-7d58-7ea1-98dd-2a4c47dbbaef" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_GainOnSaleOfIntangibleAssets_019cc503-7d58-752e-8767-8d64d4090e12" xlink:href="atex-20260331.xsd#atex_GainOnSaleOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AcquiredIndefiniteLivedIntangibleAssetsLineItems_019cc503-7d58-7f05-93f2-8732f354d50f" xlink:to="loc_atex_GainOnSaleOfIntangibleAssets_019cc503-7d58-752e-8767-8d64d4090e12" xlink:type="arc" order="11"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/AccruedSeveranceandOtherRelatedChargesNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#AccruedSeveranceandOtherRelatedChargesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/AccruedSeveranceandOtherRelatedChargesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cc503-7d58-722b-8365-56e7833cb697" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cc503-7d58-722b-8365-56e7833cb697" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_019cc503-7d58-7c96-8e10-b7012447e6e5" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019cc503-7d58-722b-8365-56e7833cb697" xlink:to="loc_srt_TitleOfIndividualAxis_019cc503-7d58-7c96-8e10-b7012447e6e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d58-7c96-8e10-b7012447e6e5_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_019cc503-7d58-7c96-8e10-b7012447e6e5" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d58-7c96-8e10-b7012447e6e5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d58-7211-bcd5-682dcd785c5d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_019cc503-7d58-7c96-8e10-b7012447e6e5" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d58-7211-bcd5-682dcd785c5d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_PresidentAndChiefExecutiveOfficerMember_019cc503-7d58-7403-a575-5ecbd0db8870" xlink:href="atex-20260331.xsd#atex_PresidentAndChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d58-7211-bcd5-682dcd785c5d" xlink:to="loc_atex_PresidentAndChiefExecutiveOfficerMember_019cc503-7d58-7403-a575-5ecbd0db8870" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeveranceCosts1_019cc503-7d58-72e5-884b-0c1124237155" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeveranceCosts1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_us-gaap_SeveranceCosts1_019cc503-7d58-72e5-884b-0c1124237155" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveCurrent_019e1a5a-8f50-7fbe-b55b-e0e8b5c30616" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_us-gaap_RestructuringReserveCurrent_019e1a5a-8f50-7fbe-b55b-e0e8b5c30616" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019cc503-7d58-709a-9415-6937e0c4ed6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_us-gaap_RestructuringAndRelatedCostNumberOfPositionsEliminated_019cc503-7d58-709a-9415-6937e0c4ed6e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_019cc503-7d58-756e-838a-227e3fd66bb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_019cc503-7d58-756e-838a-227e3fd66bb0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SeveranceCostsContinuedHealthCareCoverage_019cc503-7d58-7a86-ab78-074a1a710dfb" xlink:href="atex-20260331.xsd#atex_SeveranceCostsContinuedHealthCareCoverage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_atex_SeveranceCostsContinuedHealthCareCoverage_019cc503-7d58-7a86-ab78-074a1a710dfb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SeveranceAndOtherRelatedCharges_019cc503-7d58-7db8-a9e1-f54b35752647" xlink:href="atex-20260331.xsd#atex_SeveranceAndOtherRelatedCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_atex_SeveranceAndOtherRelatedCharges_019cc503-7d58-7db8-a9e1-f54b35752647" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_AccruedSeveranceAndOtherRelatedChargesCurrent_019cc503-7d58-7644-9522-45b772a71032" xlink:href="atex-20260331.xsd#atex_AccruedSeveranceAndOtherRelatedChargesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019cc503-7d58-736f-a155-ed8c3b462d27" xlink:to="loc_atex_AccruedSeveranceAndOtherRelatedChargesCurrent_019cc503-7d58-7644-9522-45b772a71032" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/RelatedPartyTransactionsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#RelatedPartyTransactionsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/RelatedPartyTransactionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019cc503-7d58-767b-aaee-7e919d8b8c82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:to="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019cc503-7d58-767b-aaee-7e919d8b8c82" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019cc503-7d58-73c5-bf0f-574368d9972e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyTransactionsByRelatedPartyAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRelatedPartyTransactionsByRelatedPartyTable_019cc503-7d58-767b-aaee-7e919d8b8c82" xlink:to="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019cc503-7d58-73c5-bf0f-574368d9972e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019cc503-7d58-73c5-bf0f-574368d9972e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019cc503-7d58-73c5-bf0f-574368d9972e" xlink:to="loc_us-gaap_RelatedPartyDomain_019cc503-7d58-73c5-bf0f-574368d9972e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyDomain_019cc503-7d58-7ada-bbf2-314e8f40323d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RelatedPartyTransactionsByRelatedPartyAxis_019cc503-7d58-73c5-bf0f-574368d9972e" xlink:to="loc_us-gaap_RelatedPartyDomain_019cc503-7d58-7ada-bbf2-314e8f40323d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RelatedPartyMember_019cc503-7d58-7e56-8664-a74f66809d46" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RelatedPartyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyDomain_019cc503-7d58-7ada-bbf2-314e8f40323d" xlink:to="loc_us-gaap_RelatedPartyMember_019cc503-7d58-7e56-8664-a74f66809d46" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualRequisiteServicePeriod1_019cc503-7d58-7e0c-a360-476feaa39ba4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualRequisiteServicePeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualRequisiteServicePeriod1_019cc503-7d58-7e0c-a360-476feaa39ba4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_DeferredCompensationArrangementWithIndividualCashAwardGrantedAmountPerMonth_019cc503-7d58-7e0b-a3fa-b4dd576e85bc" xlink:href="atex-20260331.xsd#atex_DeferredCompensationArrangementWithIndividualCashAwardGrantedAmountPerMonth"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:to="loc_atex_DeferredCompensationArrangementWithIndividualCashAwardGrantedAmountPerMonth_019cc503-7d58-7e0b-a3fa-b4dd576e85bc" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_019cc503-7d58-7cb0-9492-a7f6cfaaaffe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:to="loc_us-gaap_DeferredCompensationArrangementWithIndividualCompensationExpense_019cc503-7d58-7cb0-9492-a7f6cfaaaffe" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherLiabilitiesCurrent_019cf5d3-0434-7c35-bd7a-a18f1c4a61f2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherLiabilitiesCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RelatedPartyTransactionLineItems_019cc503-7d58-7351-be35-8a58c97d3e9f" xlink:to="loc_us-gaap_OtherLiabilitiesCurrent_019cf5d3-0434-7c35-bd7a-a18f1c4a61f2" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/LeasesNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#LeasesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/LeasesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_atex_LeaseLineItems_019cc503-7d59-70ec-9845-4ad1189eb07b" xlink:href="atex-20260331.xsd#atex_LeaseLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LeaseTable_019cc503-7d59-7b77-bb00-079ac71404b2" xlink:href="atex-20260331.xsd#atex_LeaseTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_atex_LeaseLineItems_019cc503-7d59-70ec-9845-4ad1189eb07b" xlink:to="loc_atex_LeaseTable_019cc503-7d59-7b77-bb00-079ac71404b2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cc503-7d59-7968-814a-120dd33a63b9" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_LeaseTable_019cc503-7d59-7b77-bb00-079ac71404b2" xlink:to="loc_srt_RangeAxis_019cc503-7d59-7968-814a-120dd33a63b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d59-7968-814a-120dd33a63b9_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cc503-7d59-7968-814a-120dd33a63b9" xlink:to="loc_srt_RangeMember_019cc503-7d59-7968-814a-120dd33a63b9_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d59-7a10-b726-08a635ad36a4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cc503-7d59-7968-814a-120dd33a63b9" xlink:to="loc_srt_RangeMember_019cc503-7d59-7a10-b726-08a635ad36a4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cc503-7d59-7c72-8560-38345a2bfc51" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d59-7a10-b726-08a635ad36a4" xlink:to="loc_srt_MinimumMember_019cc503-7d59-7c72-8560-38345a2bfc51" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cc503-7d59-7a53-b7a7-342630f76e53" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d59-7a10-b726-08a635ad36a4" xlink:to="loc_srt_MaximumMember_019cc503-7d59-7a53-b7a7-342630f76e53" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019cc503-7d59-73f2-a5af-22cc3116bcd6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LessorOperatingLeaseRenewalTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_LeaseLineItems_019cc503-7d59-70ec-9845-4ad1189eb07b" xlink:to="loc_us-gaap_LessorOperatingLeaseRenewalTerm_019cc503-7d59-73f2-a5af-22cc3116bcd6" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/IncomeTaxesNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#IncomeTaxesNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/IncomeTaxesNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:href="atex-20260331.xsd#atex_IncomeTaxDisclosureLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_IncomeTaxDisclosureTable_019cc503-7d59-795e-a13b-928c5da81b7e" xlink:href="atex-20260331.xsd#atex_IncomeTaxDisclosureTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_atex_IncomeTaxDisclosureTable_019cc503-7d59-795e-a13b-928c5da81b7e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019cc503-7d59-786c-aff7-005fa1f55238" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_IncomeTaxDisclosureTable_019cc503-7d59-795e-a13b-928c5da81b7e" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019cc503-7d59-786c-aff7-005fa1f55238" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-786c-aff7-005fa1f55238_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019cc503-7d59-786c-aff7-005fa1f55238" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-786c-aff7-005fa1f55238_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-7cb6-ba21-d4ef92617f93" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019cc503-7d59-786c-aff7-005fa1f55238" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-7cb6-ba21-d4ef92617f93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DomesticCountryMember_019cc503-7d59-70f0-aae2-7be9e2274884" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DomesticCountryMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-7cb6-ba21-d4ef92617f93" xlink:to="loc_us-gaap_DomesticCountryMember_019cc503-7d59-70f0-aae2-7be9e2274884" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_019cc503-7d59-7918-b720-42aa3d52122e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019cc503-7d59-7cb6-ba21-d4ef92617f93" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_019cc503-7d59-7918-b720-42aa3d52122e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-7259-89a2-39da284edb54" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_IncomeTaxDisclosureTable_019cc503-7d59-795e-a13b-928c5da81b7e" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-7259-89a2-39da284edb54" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7259-89a2-39da284edb54_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-7259-89a2-39da284edb54" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7259-89a2-39da284edb54_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7239-9f4d-87fed659c273" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-7259-89a2-39da284edb54" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7239-9f4d-87fed659c273" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefinitelivedIntangibleAssetsMember_019cc503-7d59-7764-94b7-5b9ef7165cb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefinitelivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7239-9f4d-87fed659c273" xlink:to="loc_us-gaap_IndefinitelivedIntangibleAssetsMember_019cc503-7d59-7764-94b7-5b9ef7165cb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_OperatingLossCarryforwardsAndDeferredTaxAssetsOperatingLossCarryforwards_019cc503-7d59-78da-9a7c-1a4a8dee1dd4" xlink:href="atex-20260331.xsd#atex_OperatingLossCarryforwardsAndDeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_atex_OperatingLossCarryforwardsAndDeferredTaxAssetsOperatingLossCarryforwards_019cc503-7d59-78da-9a7c-1a4a8dee1dd4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingLossCarryforwards_019cc503-7d59-705f-b6a7-71dfbaec476f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_OperatingLossCarryforwards_019cc503-7d59-705f-b6a7-71dfbaec476f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_019cc503-7d59-7528-a150-1c7d23c747f5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsOperatingLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_DeferredTaxAssetsOperatingLossCarryforwards_019cc503-7d59-7528-a150-1c7d23c747f5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNet_019cc503-7d59-7ddc-868a-30925caf4409" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_DeferredTaxAssetsNet_019cc503-7d59-7ddc-868a-30925caf4409" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_019cc503-7d59-7e08-8c11-d65c88c6cf72" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_019cc503-7d59-7e08-8c11-d65c88c6cf72" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_019eb21f-e86c-76ea-a2f2-4355d08f7ade" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredFederalIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_DeferredFederalIncomeTaxExpenseBenefit_019eb21f-e86c-76ea-a2f2-4355d08f7ade" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_019eb21f-9d57-783b-a776-11101b63e2da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_IncomeTaxDisclosureLineItems_019cc503-7d59-7447-9760-e86b1905d07b" xlink:to="loc_us-gaap_DeferredStateAndLocalIncomeTaxExpenseBenefit_019eb21f-9d57-783b-a776-11101b63e2da" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/IncomeTaxesScheduleofNetDeferredTaxAssetsandLiabilitiesDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#IncomeTaxesScheduleofNetDeferredTaxAssetsandLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/IncomeTaxesScheduleofNetDeferredTaxAssetsandLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:href="atex-20260331.xsd#atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesTable_019cc503-7d59-7c9b-9f47-d5e1a6ebdf6d" xlink:href="atex-20260331.xsd#atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesTable_019cc503-7d59-7c9b-9f47-d5e1a6ebdf6d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-763a-93dd-0795c7125e47" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByAssetClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesTable_019cc503-7d59-7c9b-9f47-d5e1a6ebdf6d" xlink:to="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-763a-93dd-0795c7125e47" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-763a-93dd-0795c7125e47_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-763a-93dd-0795c7125e47" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-763a-93dd-0795c7125e47_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7a36-af83-48f738d420a7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByAssetClassAxis_019cc503-7d59-763a-93dd-0795c7125e47" xlink:to="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7a36-af83-48f738d420a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMember_019cc503-7d59-7a81-aa28-0703670de5c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsMeasuredOnRecurringBasisUnobservableInputReconciliationByAssetClassDomain_019cc503-7d59-7a36-af83-48f738d420a7" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMember_019cc503-7d59-7a81-aa28-0703670de5c8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment_019cc503-7d59-7d49-82a0-0f9962cc3466" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsPropertyPlantAndEquipment_019cc503-7d59-7d49-82a0-0f9962cc3466" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_019cc503-7d59-7ea9-99c6-7552c682a352" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities_019cc503-7d59-7ea9-99c6-7552c682a352" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsDeferredIncome_019cc503-7d59-7640-95ef-e5643c008181" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsDeferredIncome"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsDeferredIncome_019cc503-7d59-7640-95ef-e5643c008181" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations_019cc503-7d59-7d59-99cf-26acb330c293" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAssetRetirementObligations_019cc503-7d59-7d59-99cf-26acb330c293" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsCapitalLossCarryforwards_019cc503-7d59-79ce-8e1c-94241c064326" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsCapitalLossCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsCapitalLossCarryforwards_019cc503-7d59-79ce-8e1c-94241c064326" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_DeferredTaxAssetsOperatingLeaseLiabilities_019cc503-7d59-7e34-88cd-20f467647cef" xlink:href="atex-20260331.xsd#atex_DeferredTaxAssetsOperatingLeaseLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_atex_DeferredTaxAssetsOperatingLeaseLiabilities_019cc503-7d59-7e34-88cd-20f467647cef" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards_019cc503-7d59-7887-b27e-361c0297849f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsCharitableContributionCarryforwards_019cc503-7d59-7887-b27e-361c0297849f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_019cc503-7d59-729a-8610-b1b45faedcdf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost_019cc503-7d59-729a-8610-b1b45faedcdf" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsGross_019cc503-7d59-7c6e-bf44-86419241ac7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxAssetsNetAbstract_019cc503-7d59-78f1-a508-532b57f263f7" xlink:to="loc_us-gaap_DeferredTaxAssetsGross_019cc503-7d59-7c6e-bf44-86419241ac7a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesNetAbstract_019cc503-7d59-774c-8c62-ff305e845f10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilitiesNetAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesNetAbstract_019cc503-7d59-774c-8c62-ff305e845f10" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_DeferredTaxLiabilitiesRou_019cc503-7d59-7321-a2a8-1c06f1b38128" xlink:href="atex-20260331.xsd#atex_DeferredTaxLiabilitiesRou"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesNetAbstract_019cc503-7d59-774c-8c62-ff305e845f10" xlink:to="loc_atex_DeferredTaxLiabilitiesRou_019cc503-7d59-7321-a2a8-1c06f1b38128" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_019cc503-7d59-7ea2-83e1-ce2cdd4154ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesNetAbstract_019cc503-7d59-774c-8c62-ff305e845f10" xlink:to="loc_us-gaap_DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsIntangibleAssets_019cc503-7d59-7ea2-83e1-ce2cdd4154ef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredIncomeTaxLiabilities_019cc503-7d59-7acb-ac01-d289252419c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredIncomeTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DeferredTaxLiabilitiesNetAbstract_019cc503-7d59-774c-8c62-ff305e845f10" xlink:to="loc_us-gaap_DeferredIncomeTaxLiabilities_019cc503-7d59-7acb-ac01-d289252419c9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_DeferredTaxAssetsLiabilitiesBeforeValuationAllowance_019cc503-7d59-7b63-8f23-24f290c9fcac" xlink:href="atex-20260331.xsd#atex_DeferredTaxAssetsLiabilitiesBeforeValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_atex_DeferredTaxAssetsLiabilitiesBeforeValuationAllowance_019cc503-7d59-7b63-8f23-24f290c9fcac" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxAssetsValuationAllowance_019cc503-7d59-77c8-af0b-754d63434870" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxAssetsValuationAllowance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_us-gaap_DeferredTaxAssetsValuationAllowance_019cc503-7d59-77c8-af0b-754d63434870" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredTaxLiabilities_019cc503-7d59-7b92-a26e-d3b553882361" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_ComponentsOfDeferredTaxAssetsAndLiabilitiesLineItems_019cc503-7d59-7432-944c-97067f590cde" xlink:to="loc_us-gaap_DeferredTaxLiabilities_019cc503-7d59-7b92-a26e-d3b553882361" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/IncomeTaxesIncomeTaxesPaidDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#IncomeTaxesIncomeTaxesPaidDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/IncomeTaxesIncomeTaxesPaidDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019cf636-7f45-7dee-88d7-da9cce23aeb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019cf636-7f45-76f0-ab77-930f21354c1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidByIndividualJurisdictionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019cf636-7f45-7dee-88d7-da9cce23aeb9" xlink:to="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019cf636-7f45-76f0-ab77-930f21354c1e" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityAxis_019cf636-7f45-7d47-bac8-b5b11617694b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionTable_019cf636-7f45-76f0-ab77-930f21354c1e" xlink:to="loc_us-gaap_IncomeTaxAuthorityAxis_019cf636-7f45-7d47-bac8-b5b11617694b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019cf636-7f45-7d47-bac8-b5b11617694b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019cf636-7f45-7d47-bac8-b5b11617694b" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019cf636-7f45-7d47-bac8-b5b11617694b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxAuthorityDomain_019cf636-7f45-70e9-a2b1-aef33e8c7c62" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxAuthorityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IncomeTaxAuthorityAxis_019cf636-7f45-7d47-bac8-b5b11617694b" xlink:to="loc_us-gaap_IncomeTaxAuthorityDomain_019cf636-7f45-70e9-a2b1-aef33e8c7c62" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalJurisdictionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxAuthorityDomain_019cf636-7f45-70e9-a2b1-aef33e8c7c62" xlink:to="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_CO_019cf636-7f45-7cae-ae2f-9a5a3be0da38" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_CO"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_stpr_CO_019cf636-7f45-7cae-ae2f-9a5a3be0da38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_WA_019e00cc-b1db-7aea-9fe8-5a081ed1f32d" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_WA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_stpr_WA_019e00cc-b1db-7aea-9fe8-5a081ed1f32d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_IL_019e00cc-f685-7506-9dfb-ce17c418aa17" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_IL"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_stpr_IL_019e00cc-f685-7506-9dfb-ce17c418aa17" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_MN_019cf636-7f45-70fd-9f1e-d47c16730be8" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_MN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_stpr_MN_019cf636-7f45-70fd-9f1e-d47c16730be8" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_stpr_VA_019e00cd-403c-7e4b-93da-b43f5e281293" xlink:href="https://xbrl.sec.gov/stpr/2025/stpr-2025.xsd#stpr_VA"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_stpr_VA_019e00cd-403c-7e4b-93da-b43f5e281293" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019cf636-7f45-79a3-ae91-85b57f0f2b85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StateAndLocalTaxJurisdictionOtherMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StateAndLocalJurisdictionMember_019cf637-ba61-7523-93a8-ed5d0e196ff8" xlink:to="loc_us-gaap_StateAndLocalTaxJurisdictionOtherMember_019cf636-7f45-79a3-ae91-85b57f0f2b85" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019cf636-7f45-7af2-bdf8-0c26bb0324c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidFederalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019cf636-7f45-7dee-88d7-da9cce23aeb9" xlink:to="loc_us-gaap_IncomeTaxPaidFederalAfterRefundReceived_019cf636-7f45-7af2-bdf8-0c26bb0324c2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019cf636-7f45-70cb-ac2a-5b6388083959" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019cf636-7f45-7dee-88d7-da9cce23aeb9" xlink:to="loc_us-gaap_IncomeTaxPaidStateAndLocalAfterRefundReceived_019cf636-7f45-70cb-ac2a-5b6388083959" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxesPaidNet_019cf636-7f45-75f6-91bb-6471aebaec5a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxesPaidNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncomeTaxPaidByIndividualJurisdictionLineItems_019cf636-7f45-7dee-88d7-da9cce23aeb9" xlink:to="loc_us-gaap_IncomeTaxesPaidNet_019cf636-7f45-75f6-91bb-6471aebaec5a" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameAxis_019cc503-7d59-78e7-b14c-bcc313733564" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_us-gaap_PlanNameAxis_019cc503-7d59-78e7-b14c-bcc313733564" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019cc503-7d59-78e7-b14c-bcc313733564_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PlanNameAxis_019cc503-7d59-78e7-b14c-bcc313733564" xlink:to="loc_us-gaap_PlanNameDomain_019cc503-7d59-78e7-b14c-bcc313733564_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PlanNameDomain_019cc503-7d59-7864-b298-95e02cc43f27" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PlanNameAxis_019cc503-7d59-78e7-b14c-bcc313733564" xlink:to="loc_us-gaap_PlanNameDomain_019cc503-7d59-7864-b298-95e02cc43f27" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_A2023StockPlanMember_019cc503-7d59-75af-847d-d9707b0bba8e" xlink:href="atex-20260331.xsd#atex_A2023StockPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PlanNameDomain_019cc503-7d59-7864-b298-95e02cc43f27" xlink:to="loc_atex_A2023StockPlanMember_019cc503-7d59-75af-847d-d9707b0bba8e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7d59-74ad-886f-74516afcf80f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7d59-74ad-886f-74516afcf80f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-74ad-886f-74516afcf80f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-74ad-886f-74516afcf80f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-74ad-886f-74516afcf80f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-74ad-886f-74516afcf80f" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_019cc503-7d59-74c8-a1de-161d49112544" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_us-gaap_RestrictedStockMember_019cc503-7d59-74c8-a1de-161d49112544" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_PerformanceStockUnitsMember_019cc503-7d59-7d49-ac77-37774bf8a545" xlink:href="atex-20260331.xsd#atex_PerformanceStockUnitsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_atex_PerformanceStockUnitsMember_019cc503-7d59-7d49-ac77-37774bf8a545" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_UnvestedTimeBasedMember_019cc503-7d59-71f6-9c74-7f7af16c382f" xlink:href="atex-20260331.xsd#atex_UnvestedTimeBasedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_atex_UnvestedTimeBasedMember_019cc503-7d59-71f6-9c74-7f7af16c382f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_PerformanceBasedRestrictedStockMember_019cc503-7d59-7a65-83e7-0134f52bcdb1" xlink:href="atex-20260331.xsd#atex_PerformanceBasedRestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_atex_PerformanceBasedRestrictedStockMember_019cc503-7d59-7a65-83e7-0134f52bcdb1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TimeBasedStockOptionsMember_019cc503-7d59-783e-bbe6-0271b428e943" xlink:href="atex-20260331.xsd#atex_TimeBasedStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_atex_TimeBasedStockOptionsMember_019cc503-7d59-783e-bbe6-0271b428e943" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ServiceStockOptionsMember_019cc503-7d59-7eb1-aa89-5749ad3facd8" xlink:href="atex-20260331.xsd#atex_ServiceStockOptionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_atex_ServiceStockOptionsMember_019cc503-7d59-7eb1-aa89-5749ad3facd8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d59-7963-b14c-acb33fb0c1a9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d59-7963-b14c-acb33fb0c1a9" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019cc503-7d59-7fc5-b174-2b5c63243c77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7330-bc3d-51431c7c8f73" xlink:to="loc_us-gaap_PerformanceSharesMember_019cc503-7d59-7fc5-b174-2b5c63243c77" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_MetricAxis_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb" xlink:href="atex-20260331.xsd#atex_MetricAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_atex_MetricAxis_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_MetricDomain_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb_default" xlink:href="atex-20260331.xsd#atex_MetricDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_atex_MetricAxis_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb" xlink:to="loc_atex_MetricDomain_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_MetricDomain_019cc503-7d59-7c5d-869c-e0e616e5788c" xlink:href="atex-20260331.xsd#atex_MetricDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_atex_MetricAxis_019cc503-7d59-71f3-88cc-a9f3c2cbdfbb" xlink:to="loc_atex_MetricDomain_019cc503-7d59-7c5d-869c-e0e616e5788c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CumulativeSpectrumProceedsMonetizedMember_019cc503-7d59-7365-879b-bcc0c518fce8" xlink:href="atex-20260331.xsd#atex_CumulativeSpectrumProceedsMonetizedMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_MetricDomain_019cc503-7d59-7c5d-869c-e0e616e5788c" xlink:to="loc_atex_CumulativeSpectrumProceedsMonetizedMember_019cc503-7d59-7365-879b-bcc0c518fce8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_TotalStockholdersReturnMember_019cc503-7d59-77db-9bd6-fa604f5b533e" xlink:href="atex-20260331.xsd#atex_TotalStockholdersReturnMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_atex_MetricDomain_019cc503-7d59-7c5d-869c-e0e616e5788c" xlink:to="loc_atex_TotalStockholdersReturnMember_019cc503-7d59-77db-9bd6-fa604f5b533e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cc503-7d59-7782-aa91-1195c55d6deb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_srt_RangeAxis_019cc503-7d59-7782-aa91-1195c55d6deb" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d59-7782-aa91-1195c55d6deb_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cc503-7d59-7782-aa91-1195c55d6deb" xlink:to="loc_srt_RangeMember_019cc503-7d59-7782-aa91-1195c55d6deb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7d59-7b1e-8363-5b47894cbd00" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cc503-7d59-7782-aa91-1195c55d6deb" xlink:to="loc_srt_RangeMember_019cc503-7d59-7b1e-8363-5b47894cbd00" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cc503-7d59-7554-82c0-d34fd75ec713" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d59-7b1e-8363-5b47894cbd00" xlink:to="loc_srt_MinimumMember_019cc503-7d59-7554-82c0-d34fd75ec713" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cc503-7d59-750e-958a-395450bfbd38" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7d59-7b1e-8363-5b47894cbd00" xlink:to="loc_srt_MaximumMember_019cc503-7d59-750e-958a-395450bfbd38" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualAxis_019cc503-7d59-7d2b-948e-59660cd96555" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_srt_TitleOfIndividualAxis_019cc503-7d59-7d2b-948e-59660cd96555" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d2b-948e-59660cd96555_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_TitleOfIndividualAxis_019cc503-7d59-7d2b-948e-59660cd96555" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d2b-948e-59660cd96555_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d4c-b509-8e8b2a6f183c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_TitleOfIndividualWithRelationshipToEntityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_TitleOfIndividualAxis_019cc503-7d59-7d2b-948e-59660cd96555" xlink:to="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d4c-b509-8e8b2a6f183c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_PresidentAndChiefExecutiveOfficerMember_019cc503-7d59-7440-a698-4bfa66ad105a" xlink:href="atex-20260331.xsd#atex_PresidentAndChiefExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d4c-b509-8e8b2a6f183c" xlink:to="loc_atex_PresidentAndChiefExecutiveOfficerMember_019cc503-7d59-7440-a698-4bfa66ad105a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SeniorExecutiveOfficerMember_019cc503-7d59-70d3-94a3-16cdc0cab2a6" xlink:href="atex-20260331.xsd#atex_SeniorExecutiveOfficerMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_TitleOfIndividualWithRelationshipToEntityDomain_019cc503-7d59-7d4c-b509-8e8b2a6f183c" xlink:to="loc_atex_SeniorExecutiveOfficerMember_019cc503-7d59-70d3-94a3-16cdc0cab2a6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingAxis_019cc503-7d59-7479-b561-c239f5d717c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-78c2-944c-f711b3c93131" xlink:to="loc_us-gaap_VestingAxis_019cc503-7d59-7479-b561-c239f5d717c2" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019cc503-7d59-7479-b561-c239f5d717c2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_VestingAxis_019cc503-7d59-7479-b561-c239f5d717c2" xlink:to="loc_us-gaap_VestingDomain_019cc503-7d59-7479-b561-c239f5d717c2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_VestingDomain_019cc503-7d59-73fe-9d09-be8e510f7f85" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_VestingDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_VestingAxis_019cc503-7d59-7479-b561-c239f5d717c2" xlink:to="loc_us-gaap_VestingDomain_019cc503-7d59-73fe-9d09-be8e510f7f85" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019cc503-7d59-7276-b498-361783f63a39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAwardTrancheOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019cc503-7d59-73fe-9d09-be8e510f7f85" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheOneMember_019cc503-7d59-7276-b498-361783f63a39" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019cc503-7d59-7303-8210-29ff7e0f2da4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAwardTrancheTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019cc503-7d59-73fe-9d09-be8e510f7f85" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheTwoMember_019cc503-7d59-7303-8210-29ff7e0f2da4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_019cc503-7d59-7a75-9dbd-71658f2f87cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationAwardTrancheThreeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_VestingDomain_019cc503-7d59-73fe-9d09-be8e510f7f85" xlink:to="loc_us-gaap_ShareBasedCompensationAwardTrancheThreeMember_019cc503-7d59-7a75-9dbd-71658f2f87cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019cc503-7d59-7626-8346-a8f3c42d7e7b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockCapitalSharesReservedForFutureIssuance"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_CommonStockCapitalSharesReservedForFutureIssuance_019cc503-7d59-7626-8346-a8f3c42d7e7b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019cc503-7d59-7392-afa5-4e393273e91c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant_019cc503-7d59-7392-afa5-4e393273e91c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_019cc503-7d59-78bd-a57b-055c8ee332da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensationGross_019cc503-7d59-78bd-a57b-055c8ee332da" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GeneralAndAdministrativeExpense_019cc503-7d59-7a46-be4a-e28e146baeba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_GeneralAndAdministrativeExpense_019cc503-7d59-7a46-be4a-e28e146baeba" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019cc503-7d59-79b1-84f3-5d9c4c49ba60" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019cc503-7d59-79b1-84f3-5d9c4c49ba60" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingAndMarketingExpense_019cc503-7d59-7cf7-8013-3b711eb6980a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingAndMarketingExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_SellingAndMarketingExpense_019cc503-7d59-7cf7-8013-3b711eb6980a" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019cc503-7d59-733f-b3bf-a569ec0aed6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions_019cc503-7d59-733f-b3bf-a569ec0aed6d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cc503-7d59-7802-8ddc-4319cecb8e7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1_019cc503-7d59-7802-8ddc-4319cecb8e7d" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cc503-7d59-7491-b694-e56ebd5ab6ed" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cc503-7d59-7491-b694-e56ebd5ab6ed" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOptionalExtensionPeriod_019cc503-7d59-7d41-8835-55ddaef4833f" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOptionalExtensionPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsOptionalExtensionPeriod_019cc503-7d59-7d41-8835-55ddaef4833f" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingIfTargetMetricAchieved_019cc503-7d59-7924-92f9-2574e4f4eced" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingIfTargetMetricAchieved"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestingIfTargetMetricAchieved_019cc503-7d59-7924-92f9-2574e4f4eced" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cc503-7d59-72b5-9dae-673cf360712b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cc503-7d59-72b5-9dae-673cf360712b" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockOptionPlanExpense_019cc503-7d59-70ed-84f4-54debf911852" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockOptionPlanExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_StockOptionPlanExpense_019cc503-7d59-70ed-84f4-54debf911852" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingRequirementsAnnualCompoundGrowthRateUsedToCalculateStockPriceLevels_019cc503-7d59-7241-a73c-349db5b3a113" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingRequirementsAnnualCompoundGrowthRateUsedToCalculateStockPriceLevels"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingRequirementsAnnualCompoundGrowthRateUsedToCalculateStockPriceLevels_019cc503-7d59-7241-a73c-349db5b3a113" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonStockTradingDayPeriod_019cc503-7d59-799c-8916-883124d67af8" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonStockTradingDayPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardCommonStockTradingDayPeriod_019cc503-7d59-799c-8916-883124d67af8" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019cc503-7d59-741e-a090-e36f5e3f8076" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardAwardVestingRightsPercentage_019cc503-7d59-741e-a090-e36f5e3f8076" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cc503-7d59-74ea-8431-17f8c59dd07c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cc503-7d59-74ea-8431-17f8c59dd07c" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019cc503-7d59-7f00-bd57-b538d2f10a13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1_019cc503-7d59-7f00-bd57-b538d2f10a13" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_019cc503-7d59-7e6a-9a30-5f9064b5b5da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardPlanModificationIncrementalCompensationCost_019cc503-7d59-7e6a-9a30-5f9064b5b5da" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedPaymentArrangementPlanModificationImmediateIncrementalCost_019cc503-7d59-78c5-823f-7620228d3cee" xlink:href="atex-20260331.xsd#atex_ShareBasedPaymentArrangementPlanModificationImmediateIncrementalCost"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedPaymentArrangementPlanModificationImmediateIncrementalCost_019cc503-7d59-78c5-823f-7620228d3cee" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019cc503-7d59-7926-8cfc-aaf9540d4523" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue_019cc503-7d59-7926-8cfc-aaf9540d4523" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7ae1-a928-6530f95266fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7ae1-a928-6530f95266fd" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019cc503-7d59-709f-a714-04ba3e54c1a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions_019cc503-7d59-709f-a714-04ba3e54c1a6" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockPricePeriodForAwardVesting_019cc503-7d59-7c73-9503-f8d87a5cf1e2" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockPricePeriodForAwardVesting"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardStockPricePeriodForAwardVesting_019cc503-7d59-7c73-9503-f8d87a5cf1e2" xlink:type="arc" order="23"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetAwardVestingPercentage_019cc503-7d59-7f57-8c6b-5e9e9182a5b5" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetAwardVestingPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardTargetAwardVestingPercentage_019cc503-7d59-7f57-8c6b-5e9e9182a5b5" xlink:type="arc" order="24"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cc503-7d59-79fd-8f1f-4cd4f83e193a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AllocatedShareBasedCompensationExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_AllocatedShareBasedCompensationExpense_019cc503-7d59-79fd-8f1f-4cd4f83e193a" xlink:type="arc" order="25"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardedInPeriod_019cc503-7d59-700e-a621-2efca92b14d1" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsAwardedInPeriod_019cc503-7d59-700e-a621-2efca92b14d1" xlink:type="arc" order="26"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019cc503-7d59-7288-b30b-fef309673faf" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StockRepurchaseProgramAuthorizedAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_srt_StockRepurchaseProgramAuthorizedAmount1_019cc503-7d59-7288-b30b-fef309673faf" xlink:type="arc" order="27"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ExciseAndSalesTaxes_019cc503-7d59-73aa-871d-309172cc0e83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ExciseAndSalesTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_ExciseAndSalesTaxes_019cc503-7d59-73aa-871d-309172cc0e83" xlink:type="arc" order="28"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019cc503-7d59-75b0-9154-116f19b580f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7286-9002-1b32af04b91e" xlink:to="loc_us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1_019cc503-7d59-75b0-9154-116f19b580f8" xlink:type="arc" order="29"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationSummaryofRestrictedStockandRestrictedStockUnitsActivityDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationSummaryofRestrictedStockandRestrictedStockUnitsActivityDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationSummaryofRestrictedStockandRestrictedStockUnitsActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7612-9e1b-8c8839c0e0c6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-790d-9fab-64382d6c77ee" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7612-9e1b-8c8839c0e0c6" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-790d-9fab-64382d6c77ee" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7494-b5b1-12b43c240c3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-790d-9fab-64382d6c77ee" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7494-b5b1-12b43c240c3d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7494-b5b1-12b43c240c3d_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7494-b5b1-12b43c240c3d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7494-b5b1-12b43c240c3d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-75e6-81b1-31c30997c787" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7494-b5b1-12b43c240c3d" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-75e6-81b1-31c30997c787" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_019cc503-7d59-765e-8c04-77feb5f6d952" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-75e6-81b1-31c30997c787" xlink:to="loc_us-gaap_RestrictedStockMember_019cc503-7d59-765e-8c04-77feb5f6d952" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7612-9e1b-8c8839c0e0c6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cc503-7d59-73ca-a0ab-aadbe970bc91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cc503-7d59-73ca-a0ab-aadbe970bc91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cc503-7d59-723f-adae-d9f0204d4ab5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod_019cc503-7d59-723f-adae-d9f0204d4ab5" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cc503-7d59-7d47-8b73-eeea81780b83" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod_019cc503-7d59-7d47-8b73-eeea81780b83" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cc503-7d59-7765-b304-9cfa9321d00e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsOutstandingRollForward_019cc503-7d59-763d-8f1b-92c70d82d0c9" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod_019cc503-7d59-7765-b304-9cfa9321d00e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber_019cc503-7d59-7535-9c8b-6d210c59ba6b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7612-9e1b-8c8839c0e0c6" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cc503-7d59-7db8-bfde-aaee66e8861c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cc503-7d59-7db8-bfde-aaee66e8861c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7dab-a520-5ce899139127" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7dab-a520-5ce899139127" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7c81-bc04-f7116006daf6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7c81-bc04-f7116006daf6" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019cc503-7d59-7c45-97c8-4176f9dbc11f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValueRollForward_019cc503-7d59-79f1-87c3-3c6b0916284b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue_019cc503-7d59-7c45-97c8-4176f9dbc11f" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue_019cc503-7d59-778b-b614-a4391ee308be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationActivityofRestrictedStockDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationActivityofRestrictedStockDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationActivityofRestrictedStockDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7a20-9c59-0d3dc3fa28c8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7ddf-bb5d-a0bb468ef355" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7a20-9c59-0d3dc3fa28c8" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7ddf-bb5d-a0bb468ef355" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7d59-77e8-a79d-cb57ad86c5fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7ddf-bb5d-a0bb468ef355" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7d59-77e8-a79d-cb57ad86c5fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-77e8-a79d-cb57ad86c5fa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-77e8-a79d-cb57ad86c5fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-77e8-a79d-cb57ad86c5fa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7168-8e93-875018d80f11" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-77e8-a79d-cb57ad86c5fa" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7168-8e93-875018d80f11" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedStockMember_019cc503-7d59-7b82-a726-65845b6a47a3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestrictedStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7168-8e93-875018d80f11" xlink:to="loc_us-gaap_RestrictedStockMember_019cc503-7d59-7b82-a726-65845b6a47a3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7fd1-a65b-3011450808e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7a20-9c59-0d3dc3fa28c8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7d59-7fd1-a65b-3011450808e4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019cc503-7d59-70b7-a15b-5271b38e32f8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7a20-9c59-0d3dc3fa28c8" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue_019cc503-7d59-70b7-a15b-5271b38e32f8" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationSummaryofStockOptionActivityDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationSummaryofStockOptionActivityDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationSummaryofStockOptionActivityDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7904-8600-80f50383c9be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7904-8600-80f50383c9be" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7120-8d5f-ed958a9a8987" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7d59-7904-8600-80f50383c9be" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7120-8d5f-ed958a9a8987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7120-8d5f-ed958a9a8987_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7120-8d5f-ed958a9a8987" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7120-8d5f-ed958a9a8987_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7bd7-bcb7-957fcfa8cd7d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7d59-7120-8d5f-ed958a9a8987" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7bd7-bcb7-957fcfa8cd7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d59-73d4-9d2c-4c9521d617dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7d59-7bd7-bcb7-957fcfa8cd7d" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cc503-7d59-73d4-9d2c-4c9521d617dd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7d59-7d3a-8478-589398164a8f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7d59-7d3a-8478-589398164a8f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cc503-7d59-7ae7-9c31-c62e1a76f762" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cc503-7d59-7ae7-9c31-c62e1a76f762" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7d59-797f-951b-642b2c97e739" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7d59-797f-951b-642b2c97e739" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_019cc503-7d59-72e2-b63a-0d7becf1cc90" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7d59-7141-a28f-ff8cb7dae234" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_019cc503-7d59-72e2-b63a-0d7becf1cc90" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7e21-729a-80ba-3dd7cd105f37" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_019cc503-7e21-706f-bf77-644cf6128dbe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber_019cc503-7e21-706f-bf77-644cf6128dbe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019cc503-7e21-7514-881a-d659229c4bcb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber_019cc503-7e21-7514-881a-d659229c4bcb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-798b-be55-f66ecaa1ca3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-798b-be55-f66ecaa1ca3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019cc503-7e21-72f3-8c4d-2f269c2e3489" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019cc503-7e21-72f3-8c4d-2f269c2e3489" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019cc503-7e21-7a30-8f82-f4ef739133e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019cc503-7e21-7a30-8f82-f4ef739133e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_019cc503-7e21-73e0-9ef0-7da0313472e4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-778a-940b-816164d99603" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_019cc503-7e21-73e0-9ef0-7da0313472e4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-7eda-a9f6-037a76497867" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_019cc503-7e21-73d3-8e0f-aa1e1db4d506" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableWeightedAverageExercisePrice_019cc503-7e21-73d3-8e0f-aa1e1db4d506" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_019cc503-7e21-7692-8c69-8786a2a6df26" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice_019cc503-7e21-7692-8c69-8786a2a6df26" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7d59-7ca5-8fe6-f029cbb527cd" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019cc503-7e21-79fa-b70d-15aa90bbb743" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2_019cc503-7e21-79fa-b70d-15aa90bbb743" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_019cc503-7e21-70b1-a707-6945c8c7517d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableWeightedAverageRemainingContractualTerm1_019cc503-7e21-70b1-a707-6945c8c7517d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_019cc503-7e21-7ba3-bc0d-dcf760a4fcec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageRemainingContractualTerm1_019cc503-7e21-7ba3-bc0d-dcf760a4fcec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019cc503-7e21-79f3-a505-9d45e7076e6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue_019cc503-7e21-79f3-a505-9d45e7076e6e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_019cc503-7e21-7008-bd9d-1725ab7eded4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1_019cc503-7e21-7008-bd9d-1725ab7eded4" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019cc503-7e21-79b1-9ac0-a45cccb43dc6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsAdditionalDisclosuresAbstract_019cc503-7e21-79c4-adf0-e4bd56eb9e6b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingAggregateIntrinsicValue_019cc503-7e21-79b1-9ac0-a45cccb43dc6" xlink:type="arc" order="6"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofOptionsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofOptionsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofOptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7eab-840f-172c92062ecf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7eab-840f-172c92062ecf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7af2-bf55-e95c995a699b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7eab-840f-172c92062ecf" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7af2-bf55-e95c995a699b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7af2-bf55-e95c995a699b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7af2-bf55-e95c995a699b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7af2-bf55-e95c995a699b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-75c4-b817-21140caa3f8c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7af2-bf55-e95c995a699b" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-75c4-b817-21140caa3f8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019cc503-7e21-7079-9ef0-60c1e6f9d48b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-75c4-b817-21140caa3f8c" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019cc503-7e21-7079-9ef0-60c1e6f9d48b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cc503-7e21-7aa7-a234-d24d04d4b9a4" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7eab-840f-172c92062ecf" xlink:to="loc_srt_RangeAxis_019cc503-7e21-7aa7-a234-d24d04d4b9a4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7e21-7aa7-a234-d24d04d4b9a4_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cc503-7e21-7aa7-a234-d24d04d4b9a4" xlink:to="loc_srt_RangeMember_019cc503-7e21-7aa7-a234-d24d04d4b9a4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cc503-7e21-7c0d-b643-97b2f74d32e8" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cc503-7e21-7aa7-a234-d24d04d4b9a4" xlink:to="loc_srt_RangeMember_019cc503-7e21-7c0d-b643-97b2f74d32e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cc503-7e21-7acf-b71c-51bdbf521d79" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7e21-7c0d-b643-97b2f74d32e8" xlink:to="loc_srt_MinimumMember_019cc503-7e21-7acf-b71c-51bdbf521d79" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cc503-7e21-78a9-8408-3e695840fc16" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cc503-7e21-7c0d-b643-97b2f74d32e8" xlink:to="loc_srt_MaximumMember_019cc503-7e21-78a9-8408-3e695840fc16" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cc503-7e21-7786-982d-0fb1a2a2fad6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cc503-7e21-7786-982d-0fb1a2a2fad6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7e21-7034-96e9-9f8d348a1139" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7e21-7034-96e9-9f8d348a1139" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cc503-7e21-773c-8f2d-bc8911aa8978" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cc503-7e21-773c-8f2d-bc8911aa8978" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cc503-7e21-70ee-a2a0-967cfaacb584" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cc503-7e21-70ee-a2a0-967cfaacb584" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_019cc503-7e21-7c3b-97ec-190373062d92" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_019cc503-7e21-7c3b-97ec-190373062d92" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7e21-705a-a7f7-93d757b8eb8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019cc503-7e21-733d-b79d-86e5c264655a" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue_019cc503-7e21-705a-a7f7-93d757b8eb8e" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationSummaryofPerformanceStockOptionsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationSummaryofPerformanceStockOptionsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationSummaryofPerformanceStockOptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7cb0-974d-ee69941d0d84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7b9c-bbef-50ad14638341" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7cb0-974d-ee69941d0d84" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7b9c-bbef-50ad14638341" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7975-9bd6-d714556f1534" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7b9c-bbef-50ad14638341" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7975-9bd6-d714556f1534" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7975-9bd6-d714556f1534_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7975-9bd6-d714556f1534" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7975-9bd6-d714556f1534_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-70a3-8830-8bc5410b87a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7975-9bd6-d714556f1534" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-70a3-8830-8bc5410b87a0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019cc503-7e21-70c6-ae82-7641a2b2360c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-70a3-8830-8bc5410b87a0" xlink:to="loc_us-gaap_PerformanceSharesMember_019cc503-7e21-70c6-ae82-7641a2b2360c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7cb0-974d-ee69941d0d84" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7e21-7282-a87b-354a16f657e8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7e21-7282-a87b-354a16f657e8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cc503-7e21-7b2b-bd38-f0575c662c4a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross_019cc503-7e21-7b2b-bd38-f0575c662c4a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7e21-7ed7-bfa3-3a01c8398868" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019cc503-7e21-7ed7-bfa3-3a01c8398868" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_019cc503-7e21-7679-b4e9-0412a872ca8b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingRollForward_019cc503-7e21-756c-9740-ab8fe18f4b10" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriod_019cc503-7e21-7679-b4e9-0412a872ca8b" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber_019cc503-7e21-7556-834c-5402de752ed9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7cb0-974d-ee69941d0d84" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-7c28-bf70-2545910089c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-7c28-bf70-2545910089c9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019cc503-7e21-74f6-a4ad-b6065a679e8d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice_019cc503-7e21-74f6-a4ad-b6065a679e8d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019cc503-7e21-7f3b-8e2c-b36ecd3d0423" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice_019cc503-7e21-7f3b-8e2c-b36ecd3d0423" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_019cc503-7e21-758e-9405-7f941976ebc7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePriceRollforward_019cc503-7e21-78ca-a318-6e3c86146482" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresAndExpirationsInPeriodWeightedAverageExercisePrice_019cc503-7e21-758e-9405-7f941976ebc7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice_019cc503-7e21-70bb-8422-bae81681aeca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofPerformanceBasedStockOptionsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofPerformanceBasedStockOptionsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/StockCompensationScheduleofAssumptionsusedtoCalculateFairValueofPerformanceBasedStockOptionsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7421-bb07-defa30bfae42" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7421-bb07-defa30bfae42" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7317-8062-43e78c9ea6d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AwardTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfShareBasedCompensationArrangementsByShareBasedPaymentAwardTable_019cc503-7e21-7421-bb07-defa30bfae42" xlink:to="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7317-8062-43e78c9ea6d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7317-8062-43e78c9ea6d1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7317-8062-43e78c9ea6d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7317-8062-43e78c9ea6d1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7317-aa45-2b7b02902f4d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AwardTypeAxis_019cc503-7e21-7317-8062-43e78c9ea6d1" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7317-aa45-2b7b02902f4d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PerformanceSharesMember_019cc503-7e21-75f7-92c1-21fb36765e0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PerformanceSharesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardAwardTypeAndPlanNameDomain_019cc503-7e21-7317-aa45-2b7b02902f4d" xlink:to="loc_us-gaap_PerformanceSharesMember_019cc503-7e21-75f7-92c1-21fb36765e0f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cc503-7e21-793b-a91d-22333beae03d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate_019cc503-7e21-793b-a91d-22333beae03d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7e21-74ea-bda7-aeef457f909a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate_019cc503-7e21-74ea-bda7-aeef457f909a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cc503-7e21-76b9-93f2-67c16e95f09c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate_019cc503-7e21-76b9-93f2-67c16e95f09c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cc503-7e21-7b78-969b-cd254e59327c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardFairValueAssumptionsExpectedTerm1_019cc503-7e21-7b78-969b-cd254e59327c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_019cc503-7e21-75dc-8e13-84dd33951b56" xlink:href="atex-20260331.xsd#atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardLineItems_019cc503-7e21-7eb1-b293-7f256e4f3e18" xlink:to="loc_atex_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate_019cc503-7e21-75dc-8e13-84dd33951b56" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/ContingenciesandGuarantyScheduleofSpectrumSaleAgreementsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#ContingenciesandGuarantyScheduleofSpectrumSaleAgreementsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/ContingenciesandGuarantyScheduleofSpectrumSaleAgreementsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019dd21a-0e22-7e82-9a34-3bdde84556e9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_us-gaap_OtherCommitmentsTable_019dd21a-0e22-7e82-9a34-3bdde84556e9" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019dd21a-0e22-7fc0-85aa-229856dca029" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019dd21a-0e22-7e82-9a34-3bdde84556e9" xlink:to="loc_srt_CounterpartyNameAxis_019dd21a-0e22-7fc0-85aa-229856dca029" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-7fc0-85aa-229856dca029_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019dd21a-0e22-7fc0-85aa-229856dca029" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-7fc0-85aa-229856dca029_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019dd21a-0e22-7fc0-85aa-229856dca029" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SanDiegoGasElectricCompanyMember_019dd21a-0e22-7a3b-906b-84ee4d1cae8a" xlink:href="atex-20260331.xsd#atex_SanDiegoGasElectricCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:to="loc_atex_SanDiegoGasElectricCompanyMember_019dd21a-0e22-7a3b-906b-84ee4d1cae8a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019dd21a-0e22-7a89-bec5-560b5bc69169" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityLCRAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:to="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019dd21a-0e22-7a89-bec5-560b5bc69169" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityLCRAExpansionMember_019dd21a-0e22-7a66-b901-db8d6a9629e8" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityLCRAExpansionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:to="loc_atex_LowerColoradoRiverAuthorityLCRAExpansionMember_019dd21a-0e22-7a66-b901-db8d6a9629e8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_OncorElectricDeliveryCompanyLLCMember_019dd21a-0e22-7958-a7b6-c6e7387f1a69" xlink:href="atex-20260331.xsd#atex_OncorElectricDeliveryCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dd21a-0e22-75ae-9074-bb57e70a99e2" xlink:to="loc_atex_OncorElectricDeliveryCompanyLLCMember_019dd21a-0e22-7958-a7b6-c6e7387f1a69" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019dd21a-0e22-7b61-a64d-2bd8fb71c37b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019dd21a-0e22-7e82-9a34-3bdde84556e9" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019dd21a-0e22-7b61-a64d-2bd8fb71c37b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019dd21a-0e22-7b61-a64d-2bd8fb71c37b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019dd21a-0e22-7b61-a64d-2bd8fb71c37b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019dd21a-0e22-7b61-a64d-2bd8fb71c37b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019dd21a-0e22-79a2-8e4b-396c35157aeb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsByMajorClassAxis_019dd21a-0e22-7b61-a64d-2bd8fb71c37b" xlink:to="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019dd21a-0e22-79a2-8e4b-396c35157aeb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicensingAgreementsMember_019dd21a-0e22-7d17-a636-39f7242e8911" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicensingAgreementsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IndefiniteLivedIntangibleAssetsMajorClassNameDomain_019dd21a-0e22-79a2-8e4b-396c35157aeb" xlink:to="loc_us-gaap_LicensingAgreementsMember_019dd21a-0e22-7d17-a636-39f7242e8911" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedEstimatedConsideration_019dd21a-0e22-7e44-845e-380c036c76fe" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedEstimatedConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicensesGrantedEstimatedConsideration_019dd21a-0e22-7e44-845e-380c036c76fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedPaymentReceived_019dd21a-0e22-7924-aabe-9aab4d28419e" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedPaymentReceived"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicensesGrantedPaymentReceived_019dd21a-0e22-7924-aabe-9aab4d28419e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_RevenueRemainingPerformanceObligationPaymentsRemaining_019dd21a-0e22-79a0-a0cf-b0aa7ec090f2" xlink:href="atex-20260331.xsd#atex_RevenueRemainingPerformanceObligationPaymentsRemaining"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_RevenueRemainingPerformanceObligationPaymentsRemaining_019dd21a-0e22-79a0-a0cf-b0aa7ec090f2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedNumberOfLicenseDelivered_019dd21a-0e22-7341-bfbf-cbd9e7e677dc" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedNumberOfLicenseDelivered"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicensesGrantedNumberOfLicenseDelivered_019dd21a-0e22-7341-bfbf-cbd9e7e677dc" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicensesGrantedNumberOfLicenseRemaining_019dd21a-0e22-7239-8fe6-47e376c8e8f3" xlink:href="atex-20260331.xsd#atex_BroadbandLicensesGrantedNumberOfLicenseRemaining"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicensesGrantedNumberOfLicenseRemaining_019dd21a-0e22-7239-8fe6-47e376c8e8f3" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsCustomerCredit_019ead07-655b-75e2-b4e6-51a5ea464060" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsCustomerCredit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsCustomerCredit_019ead07-655b-75e2-b4e6-51a5ea464060" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments_019dd21e-a824-7f2a-abee-cc1a2999ce26" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicenseSaleReimbursableClearingCostsAndAntiWindfallPayments_019dd21e-a824-7f2a-abee-cc1a2999ce26" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_BroadbandLicenseConsiderationReimbursableClearingCostsAndAntiWindfallPayments_019dd21e-a824-741c-95e7-10e0f2c663d7" xlink:href="atex-20260331.xsd#atex_BroadbandLicenseConsiderationReimbursableClearingCostsAndAntiWindfallPayments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dd21a-0e22-7257-9a03-306e8a02e3f6" xlink:to="loc_atex_BroadbandLicenseConsiderationReimbursableClearingCostsAndAntiWindfallPayments_019dd21e-a824-741c-95e7-10e0f2c663d7" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/ContingenciesandGuarantyScheduleofShortTermandLongTermContingentLiabilitiesDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#ContingenciesandGuarantyScheduleofShortTermandLongTermContingentLiabilitiesDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/ContingenciesandGuarantyScheduleofShortTermandLongTermContingentLiabilitiesDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019dcfb4-f089-7a4a-9e6c-2b92d69bc085" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019dcfb4-f089-73bb-a780-fcc1f11eb0bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dcfb4-f089-7a4a-9e6c-2b92d69bc085" xlink:to="loc_us-gaap_OtherCommitmentsTable_019dcfb4-f089-73bb-a780-fcc1f11eb0bd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019e2459-d86a-707e-b3a4-26eef894666c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019dcfb4-f089-73bb-a780-fcc1f11eb0bd" xlink:to="loc_srt_CounterpartyNameAxis_019e2459-d86a-707e-b3a4-26eef894666c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-707e-b3a4-26eef894666c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019e2459-d86a-707e-b3a4-26eef894666c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-707e-b3a4-26eef894666c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019e2459-d86a-707e-b3a4-26eef894666c" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_SanDiegoGasElectricCompanyMember_019dcfb4-f089-7b54-8d5e-8498d46cab96" xlink:href="atex-20260331.xsd#atex_SanDiegoGasElectricCompanyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:to="loc_atex_SanDiegoGasElectricCompanyMember_019dcfb4-f089-7b54-8d5e-8498d46cab96" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019dcfb4-f089-7b89-8fb4-f36832a1d423" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityLCRAMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:to="loc_atex_LowerColoradoRiverAuthorityLCRAMember_019dcfb4-f089-7b89-8fb4-f36832a1d423" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_LowerColoradoRiverAuthorityLCRAExpansionMember_019dcfb4-f089-762d-a6b4-2225c6143f2e" xlink:href="atex-20260331.xsd#atex_LowerColoradoRiverAuthorityLCRAExpansionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:to="loc_atex_LowerColoradoRiverAuthorityLCRAExpansionMember_019dcfb4-f089-762d-a6b4-2225c6143f2e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_OncorElectricDeliveryCompanyLLCMember_019dcfb4-f089-7e09-99cc-9d695cf5774a" xlink:href="atex-20260331.xsd#atex_OncorElectricDeliveryCompanyLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019e2459-d86a-7c2d-a518-c02d394ee221" xlink:to="loc_atex_OncorElectricDeliveryCompanyLLCMember_019dcfb4-f089-7e09-99cc-9d695cf5774a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationCurrent_019dcfb4-f089-73a6-8a8f-d5b7584b2389" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dcfb4-f089-7a4a-9e6c-2b92d69bc085" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationCurrent_019dcfb4-f089-73a6-8a8f-d5b7584b2389" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationNoncurrent_019dcfb4-f089-7bc3-a3f1-fbfff8a1524f" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019dcfb4-f089-7a4a-9e6c-2b92d69bc085" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsContingentConsiderationNoncurrent_019dcfb4-f089-7bc3-a3f1-fbfff8a1524f" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/ContingenciesandGuarantyNarrativeDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#ContingenciesandGuarantyNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/ContingenciesandGuarantyNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherCommitmentsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019dcfc3-0dda-7de1-9395-921dae9f55ff" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:to="loc_srt_CounterpartyNameAxis_019dcfc3-0dda-7de1-9395-921dae9f55ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcfc3-0dda-7de1-9395-921dae9f55ff_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019dcfc3-0dda-7de1-9395-921dae9f55ff" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcfc3-0dda-7de1-9395-921dae9f55ff_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcfc3-0dda-72d8-b356-1bc2ce01055d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019dcfc3-0dda-7de1-9395-921dae9f55ff" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcfc3-0dda-72d8-b356-1bc2ce01055d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_XcelEnergyServicesIncMember_019dcfc3-0dda-7d41-9f8e-f91c5a855c95" xlink:href="atex-20260331.xsd#atex_XcelEnergyServicesIncMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcfc3-0dda-72d8-b356-1bc2ce01055d" xlink:to="loc_atex_XcelEnergyServicesIncMember_019dcfc3-0dda-7d41-9f8e-f91c5a855c95" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfArrangementAxis_019dcfc3-0dda-7d42-8309-e845d2393854" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfArrangementAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:to="loc_us-gaap_TypeOfArrangementAxis_019dcfc3-0dda-7d42-8309-e845d2393854" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019dcfc3-0dda-7d42-8309-e845d2393854_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019dcfc3-0dda-7d42-8309-e845d2393854" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019dcfc3-0dda-7d42-8309-e845d2393854_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019dcfc3-0dda-76e1-bf60-5df4536fe3f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ArrangementsAndNonarrangementTransactionsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TypeOfArrangementAxis_019dcfc3-0dda-7d42-8309-e845d2393854" xlink:to="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019dcfc3-0dda-76e1-bf60-5df4536fe3f0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember_019dcfc3-0dda-7929-ad28-89effb52f359" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ArrangementsAndNonarrangementTransactionsMember_019dcfc3-0dda-76e1-bf60-5df4536fe3f0" xlink:to="loc_us-gaap_CollaborativeArrangementTransactionWithPartyToCollaborativeArrangementMember_019dcfc3-0dda-7929-ad28-89effb52f359" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019dcfc3-0dda-7d56-ada7-eb5423cff9e0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:to="loc_srt_RangeAxis_019dcfc3-0dda-7d56-ada7-eb5423cff9e0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfc3-0dda-7d56-ada7-eb5423cff9e0_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019dcfc3-0dda-7d56-ada7-eb5423cff9e0" xlink:to="loc_srt_RangeMember_019dcfc3-0dda-7d56-ada7-eb5423cff9e0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019dcfc3-0dda-7320-8cb5-93ebd3f20602" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019dcfc3-0dda-7d56-ada7-eb5423cff9e0" xlink:to="loc_srt_RangeMember_019dcfc3-0dda-7320-8cb5-93ebd3f20602" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019dcfc3-0dda-7245-a7bf-ad2b1c52fcca" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019dcfc3-0dda-7320-8cb5-93ebd3f20602" xlink:to="loc_srt_MaximumMember_019dcfc3-0dda-7245-a7bf-ad2b1c52fcca" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_OtherCommitmentsTable_019cc503-7e21-702b-aefe-23a9a54fd452" xlink:to="loc_srt_ProductOrServiceAxis_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019dcfc3-0dda-731f-8537-d1bbbfc0f053" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019dcfc3-0dda-7d6d-8b7d-20a4c2ad8ec0" xlink:to="loc_srt_ProductsAndServicesDomain_019dcfc3-0dda-731f-8537-d1bbbfc0f053" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_WirelessLicensesMember_019dcfc3-0dda-7f6a-b6ae-f00b9facb86c" xlink:href="atex-20260331.xsd#atex_WirelessLicensesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019dcfc3-0dda-731f-8537-d1bbbfc0f053" xlink:to="loc_atex_WirelessLicensesMember_019dcfc3-0dda-7f6a-b6ae-f00b9facb86c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsAgreementTerm_019dcfc3-0dda-7992-a69c-f57768fcaee0" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsAgreementTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsAgreementTerm_019dcfc3-0dda-7992-a69c-f57768fcaee0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_CollaborativeArrangementRightsAndObligationsNumberOfStatesInServiceTerritory_019dcfc3-0dda-7a55-9b61-ca86cc6d152a" xlink:href="atex-20260331.xsd#atex_CollaborativeArrangementRightsAndObligationsNumberOfStatesInServiceTerritory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_atex_CollaborativeArrangementRightsAndObligationsNumberOfStatesInServiceTerritory_019dcfc3-0dda-7a55-9b61-ca86cc6d152a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiability_019dcfc3-0dda-72e0-9929-00ecbb6a5606" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_us-gaap_ContractWithCustomerLiability_019dcfc3-0dda-72e0-9929-00ecbb6a5606" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019dcfc3-0dda-7a1f-ad8d-2b5f87d0a4d4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetAcquisitionConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_us-gaap_AssetAcquisitionConsiderationTransferred_019dcfc3-0dda-7a1f-ad8d-2b5f87d0a4d4" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_019dcfc3-0dda-798f-b9ac-810fa45c6649" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherCommitmentsLineItems_019d3422-a9a1-796d-9866-9bab2e13e043" xlink:to="loc_us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount_019dcfc3-0dda-798f-b9ac-810fa45c6649" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.anterix.com/role/SubsequentEventsDetails" xlink:type="simple" xlink:href="atex-20260331.xsd#SubsequentEventsDetails"/>
  <link:definitionLink xlink:role="http://www.anterix.com/role/SubsequentEventsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventLineItems_019dcf9f-7fd8-7dbc-ae2b-5145deb0df6e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTable_019dcf9f-7fd8-7d7a-a48e-38aee3130e43" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SubsequentEventLineItems_019dcf9f-7fd8-7dbc-ae2b-5145deb0df6e" xlink:to="loc_us-gaap_SubsequentEventTable_019dcf9f-7fd8-7d7a-a48e-38aee3130e43" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_CounterpartyNameAxis_019dcf9f-7fd8-7762-b0fa-de81a7933106" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_CounterpartyNameAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019dcf9f-7fd8-7d7a-a48e-38aee3130e43" xlink:to="loc_srt_CounterpartyNameAxis_019dcf9f-7fd8-7762-b0fa-de81a7933106" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcf9f-7fd8-7762-b0fa-de81a7933106_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_CounterpartyNameAxis_019dcf9f-7fd8-7762-b0fa-de81a7933106" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcf9f-7fd8-7762-b0fa-de81a7933106_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcf9f-7fd8-75d7-bed8-75255849d03a" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RepurchaseAgreementCounterpartyNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_CounterpartyNameAxis_019dcf9f-7fd8-7762-b0fa-de81a7933106" xlink:to="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcf9f-7fd8-75d7-bed8-75255849d03a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_atex_PublicUtilityDistrictNo.1OfBentonCountyMember_019e2465-3a8a-71a1-ad27-35b004aebc8f" xlink:href="atex-20260331.xsd#atex_PublicUtilityDistrictNo.1OfBentonCountyMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RepurchaseAgreementCounterpartyNameDomain_019dcf9f-7fd8-75d7-bed8-75255849d03a" xlink:to="loc_atex_PublicUtilityDistrictNo.1OfBentonCountyMember_019e2465-3a8a-71a1-ad27-35b004aebc8f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeAxis_019dcf9f-7fd8-7e26-a964-46cc092553aa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019dcf9f-7fd8-7d7a-a48e-38aee3130e43" xlink:to="loc_us-gaap_SubsequentEventTypeAxis_019dcf9f-7fd8-7e26-a964-46cc092553aa" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019dcf9f-7fd8-7e26-a964-46cc092553aa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019dcf9f-7fd8-7e26-a964-46cc092553aa" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019dcf9f-7fd8-7e26-a964-46cc092553aa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventTypeDomain_019dcf9f-7fd8-7f42-a5a7-5727b820b746" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_SubsequentEventTypeAxis_019dcf9f-7fd8-7e26-a964-46cc092553aa" xlink:to="loc_us-gaap_SubsequentEventTypeDomain_019dcf9f-7fd8-7f42-a5a7-5727b820b746" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SubsequentEventMember_019dcfa1-2b03-7caf-9af6-3f6248c8832c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SubsequentEventMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventTypeDomain_019dcf9f-7fd8-7f42-a5a7-5727b820b746" xlink:to="loc_us-gaap_SubsequentEventMember_019dcfa1-2b03-7caf-9af6-3f6248c8832c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019eae2e-7b29-7aba-93b0-9e79f7fe8412" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_SubsequentEventTable_019dcf9f-7fd8-7d7a-a48e-38aee3130e43" xlink:to="loc_srt_ProductOrServiceAxis_019eae2e-7b29-7aba-93b0-9e79f7fe8412" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019eae2e-7b29-7aba-93b0-9e79f7fe8412_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019eae2e-7b29-7aba-93b0-9e79f7fe8412" xlink:to="loc_srt_ProductsAndServicesDomain_019eae2e-7b29-7aba-93b0-9e79f7fe8412_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019eae2e-7b29-7a1e-a0d1-d1d2fbd1873c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019eae2e-7b29-7aba-93b0-9e79f7fe8412" xlink:to="loc_srt_ProductsAndServicesDomain_019eae2e-7b29-7a1e-a0d1-d1d2fbd1873c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LicenseMember_019eae2e-9ea6-761f-908d-f283f837f99a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LicenseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019eae2e-7b29-7a1e-a0d1-d1d2fbd1873c" xlink:to="loc_us-gaap_LicenseMember_019eae2e-9ea6-761f-908d-f283f837f99a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019eae2e-4706-79aa-a7f4-2fe9461e6518" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SubsequentEventLineItems_019dcf9f-7fd8-7dbc-ae2b-5145deb0df6e" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019eae2e-4706-79aa-a7f4-2fe9461e6518" xlink:type="arc" order="0"/>
  </link:definitionLink>
</link:linkbase>
