Source : Webster's Revised Unabridged Dictionary (1913)

Piracy \Pi"ra*cy\, n.; pl. {Piracies}. [Cf. LL. piratia, Gr. ?.
   See {Pirate}.]
   1. The act or crime of a pirate.

   2. (Common Law) Robbery on the high seas; the taking of
      property from others on the open sea by open violence;
      without lawful authority, and with intent to steal; -- a
      crime answering to robbery on land.

Source : WordNet®

piracy
     n 1: robbery on the high seas; taking a ship away from the
          control of those who are legally entitled to it [syn: {buccaneering}]
     2: the act of plagiarizing; taking someone's words or ideas as
        if they were your own [syn: {plagiarism}, {plagiarization},
         {plagiarisation}]

Source : Free On-Line Dictionary of Computing

piracy
     
        {software piracy}