Defying expression or description
English: indefinable, indescribable, ineffable, unspeakable, untellable, unutterable
unutterableEnglish
unutterable, ineffable, unspeakable, indefinable, indescribable
Adjective
Too sacred to be uttered
English: ineffable, unnameable, unspeakable, unutterable
Very difficult to pronounce correctly
English: unpronounceable, unutterable