Entry 1 sense Webster, 1913 Unacceptable /ŭnˌ-ăk-sĕp'-təb-əl/ · Un·ac·cept·a·ble · IPA /ˌʌn.ækˈsɛp.tə.bl̩/ 01 a. Not acceptable; not pleasing; not welcome; unpleasant; disagreeable; displeasing; offensive. 1. Not acceptable; not pleasing; not welcome; unpleasant; disagreeable; displeasing; offensive.