pri·va·teer 
(prī′və-tîr)
(prī′və-tîr)n.
1. A ship privately owned and crewed but authorized by a government during wartime to attack and capture enemy vessels.
2. The commander or one of the crew of such a ship.
intr.v. pri·va·teered, pri·va·teer·ing, pri·va·teers
To sail as a privateer.