pi·ra·cy   (pī'rə-sē)    n.   pl. pi·ra·cies Robbery committed at sea. A similar act of robbery, as the hijacking of an airplane. The unauthorized use or reproduction of copyrighted or patented material: software piracy. The operation of an unlicensed, illegal radio or television station. [Medieval Latin pīrātia, from Late Greek peirāteia, from Greek peirātēs, pirate; see pirate.]

piracy 

Main Entry: pi·ra·cy
Pronunciation: 'pI-r&-sE
Function: noun
Inflected Form: plural -cies
1 : an act of robbery esp. on the high seas; specifically : an illegal act of violence, detention, or plunder committed for private ends by crew or passengers of a private ship or aircraft against another ship or aircraft on the high seas or in a place outside the jurisdiction of any state —see also AIRCRAFT PIRACY Article I of the CONSTITUTION in the back matter
2 a : the unauthorized copying, distribution, or use of another's production (as a film) esp. in infringement of a copyright piracy> b : the unauthorized use, interception, or receipt of encoded communications (as satellite cable programming) esp. to avoid paying fees for use piracy of programming signals —United States v. Harrell, 983 Federal Reporter, Second Series 36 (1993)>
3 : the crime of committing piracy

piracy
software piracy