Gen·tle·man:

A man whose conduct conforms to a high standard of propriety or correct behavior.

The term gentleman in its original and strict signification, denoted a well-educated man of good family and distinction.

A gentleman’s agreement is an informal agreement between two or more parties. It may be written, oral, or simply understood as part of an unspoken agreement by convention or through mutually beneficial etiquette. The essence of a gentleman’s agreement is that it relies upon the honor of the parties for its fulfillment, rather than being in any way enforceable.