in the plural Messieurs, a title of honour and respect used by the French in writing to persons of superior rank or quality.
Dukes, peers, archbishops, bishops, and presidents à la mortier, were complimented with the title of Monseigneur. In the petitions presented to the sovereign courts, they used the term Messieurs.
Monseigneur, absolutely used, was a title restrained to the dauphin of France. This custom was unknown till the time of Louis XIV, before which the dauphin was styled Monsieur le Dauphin.