The definition of an adjective is a part of speech that is used to describe a noun. Red, tall, better and fast are all examples of adjectives.
In modern parlance, a gentleman (from gentle + man, translating the Old French gentilz hom) is any man of good, courteous conduct. A gentleman may also simply be a polite term for any man, as in indications of gender-separated facilities, or as a sign of the speaker's own courtesy when addressing others. The modern female equivalent is lady.
cavalier (plural cavaliers) ( 1 historical) A military man serving on horse, (chiefly) early modern cavalry officers who had abandoned the heavy armor of medieval knights. ( 2 historical) A gallant: a sprightly young dashing military man.