of a quality befitting the court: elegant
very polite or refined, as befitting a royal court.
Other than that, each source has a slightly different addition. Merriam-Webster adds "insincerely flattering." Can anyone shed light on why that part exists? Can it also be used to describe someone who is overly polite?
Lastly, if you Google "Courtly Definition," it spits out a definition that includes "given to flattery." Can that be used to describe someone who accepted a flirtatious advance? For example, "The amount of chivalry exuded by this well-dressed man rendered the girl courtly."