Entry 1 sense Webster, 1913 Messieurs /(?; F. ?; 277)/ · Mes·sieurs · IPA /ˈmɛsə(ɹ)z/ 01 n. pl. Sirs; gentlemen; -- abbreviated to Messrs., which is used as the plural of Mr. 1. Sirs; gentlemen; -- abbreviated to Messrs., which is used as the plural of Mr.