n., pl., Mes·sieurs (mā-syœ', mĕs'ərz).
- (Abbr. M.) Used as a courtesy title before the surname, full name, or professional title of a man in a French-speaking area: Monsieur Cartier; Monsieur Jacques Cartier.
- monsieur Used as a form of polite address for a man in a French-speaking area.
[French, from Old French : mon, my (from Latin meum, accusative of meus) + sieur, lord, sir (from Vulgar Latin *seiorem, accusative of *seior; see sire).]





