/ Dictionary / Index M mustache cup: Meaning and Definition of Find definitions for: mus'tache cup" Pronunciation: [key] a cup having a straight piece inside, just below the rim, for holding back a man's mustache while he is drinking. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mustache mustachio Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language