The Collaborative International Dictionary of English v.0.48:

Pirate \Pi"rate\, v. i. [imp. & p. p. Pirated; p. pr. & vb. n.
   Pirating.] [Cf. F. pirater.]
   To play the pirate; to practice robbery on the high seas.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pirate \Pi"rate\, v. t.
   To publish, as books or writings, without the permission of
   the author.
   [1913 Webster]

         They advertised they would pirate his edition. --Pope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pirate \Pi"rate\, n. [L. pirata, Gr. ?, fr. ? to attempt,
   undertake, from making attempts or attacks on ships, ? an
   attempt, trial; akin to E. peril: cf. F. pirate. See
   Peril.]
   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.
      [1913 Webster]

   2. An armed ship or vessel which sails without a legal
      commission, for the purpose of plundering other vessels on
      the high seas.
      [1913 Webster]

   3. One who infringes the law of copyright, or publishes the
      work of an author without permission.
      [1913 Webster]

   Pirate perch (Zool.), a fresh-water percoid fish of the
      United States (Aphredoderus Sayanus). It is of a dark
      olive color, speckled with blackish spots.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pirate
    n 1: someone who uses another person's words or ideas as if they
         were his own [syn: plagiarist, plagiarizer,
         plagiariser, literary pirate, pirate]
    2: someone who robs at sea or plunders the land from the sea
       without having a commission from any sovereign nation [syn:
       pirate, buccaneer, sea robber, sea rover]
    3: a ship that is manned by pirates [syn: pirate, pirate
       ship]
    v 1: copy illegally; of published material
    2: take arbitrarily or by force; "The Cubans commandeered the
       plane and flew it to Miami" [syn: commandeer, hijack,
       highjack, pirate]

Moby Thesaurus II by Grady Ward, 1.0:

86 Moby Thesaurus words for "pirate":
   AB, Ancient Mariner, Argonaut, Blackbeard, Captain Hook,
   Captain Kidd, Dylan, Flying Dutchman, Henry Morgan, Jean Lafitte,
   Neptune, OD, Poseidon, Varuna, able seaman, able-bodied seaman,
   adopt, air pirate, airplane hijacker, appropriate, assume,
   bluejacket, borrow, buccaneer, copy, copyright infringer, corsair,
   crib, cribber, deep-sea man, derive from, fair-weather sailor,
   filibuster, fisherman, freeboot, freebooter, hearty, imitate,
   infringe, infringe a copyright, infringer, jack, jack afloat,
   jack-tar, jacky, lift, limey, literary pirate, lobsterman,
   make use of, mariner, matelot, mock, navigator, picaroon, pinch,
   plagiarist, plagiarize, plagiarizer, poach, privateer, raider,
   reproduce, rover, sailor, salt, sea, sea dog, sea king, sea rover,
   seafarer, seafaring man, seaman, shipman, simulate, skyjacker,
   steal, take, take on, take over, tar, viking, water dog, whaler,
   windjammer, windsailor



The Free On-line Dictionary of Computing (30 December 2018):

software pirate
pirate

    Someone engaged in software piracy.

   (2010-02-03)


Bouvier's Law Dictionary, Revised 6th Ed (1856):

PIRATE. A sea robber, who, to enrich himself by subtlety or open force,
setteth upon merchants and others trading by sea, despoiling them of their
loading, and sometimes bereaving them of life and, sinking their ships;
Ridley's View of the Civ. and Eccl. Law, part 2, c. 1, s. 8; or more
generally one guilty of the crime of piracy. Merl. Repert. h.t. See, for the
etymology of this word, Bac. Ab. Piracy