Entry 1 sense Webster, 1913 Impeccable /ĭmˌ-pĕk'-əb-əl/ · Im·pec·ca·ble · IPA /ɪmˈpɛkəbəl/ 01 a. Not liable to sin; exempt from the possibility of doing wrong. 1. Not liable to sin; exempt from the possibility of doing wrong. “God is infallible, impeccable, and absolutely perfect.” — P. Skelton.