a man of good family, breeding, or social position.

(used as a polite term) a man

Do you know that gentleman over there?

gentlemen, (used as a form of address)

Gentlemen, please come this way.

a civilized, educated, sensitive, or well-mannered man

He behaved like a true gentleman.

a male personal servant, esp. of a man of social position; valet.

a male attendant upon a king, queen, or other royal person, who is himself of high birth or rank.

a man of good social standing, as a noble or an armigerous commoner.

a man with an independent income who does not work for a living.

a male member of the U.S. Senate or House of Representatives

The chair recognizes the gentleman from Massachusetts.

History/Historical . a man who is above the rank of yeoman.