Entry 1 sense Webster, 1913 Taxability /tăkˌ-səb-ĭl'-ĭt-ē/ · Tax·a·bil·i·ty · IPA /tˌæksəbˈɪlɪtiː/ 01 n. The quality or state of being taxable; taxableness. 1. The quality or state of being taxable; taxableness.