/ Dictionary / Index M monsieur: Meaning and Definition of Find definitions for: mon•sieur Pronunciation: (mus-yûr' Fr. mu-syœ'), [key] — pl. mes•sieurs the conventional French title of respect and term of address for a man, corresponding to Mr. or sir. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: monsieur (Thesaurus) Monseigneur Monsignor Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language