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.
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   2. An armed ship or vessel which sails without a legal
      commission, for the purpose of plundering other vessels on
      the high seas.
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   3. One who infringes the law of copyright, or publishes the
      work of an author without permission.
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   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.
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