Dictionary

A man of gentle but not noble birth, particularly a man of means (originally ownership of property) who does not work for a living but has no official status in a peerage; an armiferous man ranking below a knight.

Example: Being a gentleman, Robert was entitled to shove other commoners into the gongpit but he still had to jump out of the way of the knights to avoid the same fate himself.

Any well-bred, well-mannered, or charming man.

An effeminate or oversophisticated man.

Example: Well, la-di-da, aren't you just a proper gentleman?

(polite term of address) Any man.

Example: Please escort this gentleman to the gentlemen's room.

Possessive case of gentlemen: belonging to some or all gentlemen.

A lavatory intended for use by men, often including urinals in addition to toilets.

Other rooms intended for use by men, as waiting rooms, dressing rooms, locker rooms, etc.