n. pl. Mes·sieurs (mā-syœ, mĕsərz)
1. 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.
2. monsieur Used as a form of polite address for a man in a French-speaking area.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.