un•men•tion•a•blePronunciation: (un-men'shu-nu-bul), [key]
not mentionable; inappropriate, unfit, or improper for mention, as in polite conversation; unspeakable.
something that is not to be mentioned: That subject was classed among the unmentionables.
(formerly) trousers or breeches.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.