Dictionary
un•ut•ter•a•ble
Pronunciation: (un-ut'ur-u-bul), [key]—
adj.
1. not communicable by utterance; unspeakable; beyond expression:
unutterable joy.
2. not utterable; not pronounceable:
an unutterable foreign word. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.