Definition of pirate :
1. 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.
2. An armed ship or vessel which sails without a legal commission, for the purpose of plundering other vessels on the high seas.
3. One who infringes the law of copyright, or publishes the work of an author without permission.
4. To play the pirate; to practice robbery on the high seas.
5. To publish, as books or writings, without the permission of the author.
pillager, plagiarist, literary pirate, raider, bandit, pirate ship, commandeer, plunderer, forager, footpad, cribber, sea robber, plagiariser, words, depredator, freebooter, buccaneer, marauder, plagiarizer, give, sea rover, despoiler, brigand, highjack
steal (part of speech: verb)
cop, grab, fleece, nip, defraud, blackmail, holdup, swipe, palm, loot, plagiarize, stickup, filch, lift, embezzle, haul, rustle, mug, rob, extort, poach, abstract, pilfer, pocket, shoplift, swindle, steal, burglarize, plunder, shanghai, heist, hijack
thief (part of speech: noun)
grafter, ranger, evildoer, cat burglar, mugger, Barbary pirate, highwayman, privateer, robber, hijacker, poacher, stealer, larcenist, housebreaker, outlaw, crook, larcener, lawbreaker, villain, soldier of fortune, burglar, filcher, corsair, lifter, prowler, thief, delinquent, criminal, thug, swindler, felon, pickpocket, culprit