What does "cavalier" mean?

Additional senses

1. 2.One of the court party in the time of king Charles L. as contrasted with a Roundhead or an adherent of Parliament. Clarendon.
2. 3.(Fort.) A work of more that ordinary heigh, rising from the level ground of a bastion, etc., and overlooking surrounding parts.
3. 4.Gay; easy; offhand; frank. The plodding, persevering scupulous accuracy of the one, and the easy, cavalier, verbal fluency of the other, from a complete contrast. Hazlitt.
4. 5.High-spirited. [Obs.] "The people are naturally not valiant, and not much cavalier." Suckling.
5. 6.Supercilious; haughty; disdainful; curt; brusque.
6. 7.Of or pertaining to the party of King Charles I. "An old Cavalier family." Beaconsfleld.