Other forms: gentlemen
A gentleman is a polite, well-behaved man. A perfect gentleman, be a gentleman, ladies and gentlemen.
The modern sense is about conduct, but the word began as a rank: a gentleman was a man entitled to bear arms and not obliged to work, which is why the phrase gentleman farmer exists. Ladies and gentlemen is the standard opening of an address. Note gentlemanly; a gentleman's agreement, binding on honour and not in law; and that gents is the British sign on a public lavatory.
1noungentlemanA polite, well-behaved man.
“He's a real gentleman who always holds the door open for others.”
2nouncertainA man of a certain rank, in older use.
“In the eighteenth century, a gentleman did not need to work for a living.”
Too few real examples of this word to estimate which sense is commonest.
gentleman is a man of good conduct.
Middle English gentilman is gentle plus man, and gentle then meant well-born, from Latin gentilis, of the same family. Genteel and gentile are the same word arriving by other routes.
Middle English
gentilman
English, today
gentleman
From Middle English gentilman, morphologically gentle + man, gentilhome.
Etymology from Wiktionary, CC BY-SA