Noun

1. A privately owned warship that had official sanction to attack enemy ships and take possession of their cargo.
2. An officer or any other member of the crew of such a ship.
3. A private individual entrant into a race or competition who does not have the backing of a large, professional team.

Verb

1. To function under official sanction permitting attacks on enemy shipping and seizing ship and cargo; to engage in government-sponsored piracy.