From Longman Dictionary of Contemporary Englishineffablein‧ef‧fa‧ble /ɪnˈefəbəl/ adjective formal GOOD/EXCELLENTtoo great to be described in words SYN indescribable ineffable joy —ineffably adverb
Examples from the Corpus
ineffable• ineffable satisfactionOrigin ineffable (1400-1500) French Latin ineffabilis, from effari “to speak out” 