unutterable/ʌnˈʌtərəbəl/1unable to be described or explainedCopySynonyms: indescribableuntellableunspeakableineffableindefinable2too sacred to be utteredCopySynonyms: unnameableineffableunspeakable3too hard to be correctly pronouncedCopySynonyms: unpronounceable