1. An armed horseman; especially, a mounted soldier or a knight: "The cavalier rode at the head of the group of ground soldiers, hoping to lead the soldiers to victory and glory."
2. Someone having the spirit or bearing of a knight; a courtly gentleman: "The young cavalier dressed in the high fashion of the court and behaved very nicely towards everyone."
3. A gallant or courteous gentleman; especially, one serving as a lady's escort: "Lady Donna asked Lord Ashton to be her cavalier for the evening at the opera."