pirate n: a person who commits piracy
: to take or appropriate by piracy
: to copy, distribute, or use without authorization esp. in infringement of copyright [the pirated software] [pirating cable signals]
: to commit piracy compare bootleg
Source: Merriam-Webster's Dictionary of Law ©1996. Merriam-Webster, Incorporated. Published under license with Merriam-Webster, Incorporated.