(1):

(n.) An armed ship or vessel which sails without a legal commission, for the purpose of plundering other vessels on the high seas.

(2):

(n.) One who infringes the law of copyright, or publishes the work of an author without permission.

(3):

(n.) A robber on the high seas; one who by open violence takes the property of another on the high seas; especially, one who makes it his business to cruise for robbery or plunder; a freebooter on the seas; also, one who steals in a harbor.

(4):

(v. t.) To publish, as books or writings, without the permission of the author.

(5):

(v. i.) To play the pirate; to practice robbery on the high seas.