Entry 1 sense Webster, 1913 Indefinable /ĭnˌ-dĭf-īn'-əb-əl/ · In·de·fin·a·ble · IPA /ˌɪndɪfˈaɪnəbəl/ 01 a. Incapable of being defined or described; inexplicable. 1. Incapable of being defined or described; inexplicable.