piracy

noun, plural pi·ra·cies.

1. practice of a pirate; robbery or illegal violence at sea.
2. the unauthorized reproduction or use of a copyrighted book, recording, television program, patented invention, trademarked product, etc.: The record industry is beset with piracy.
3. Also called stream capture. Geology. diversion of the upper part of one stream by the headward growth of another.

noun plural -cies

1. British robbery on the seas within admiralty jurisdiction
2. a felony, such as robbery or hijacking, committed aboard a ship or aircraft
3. the unauthorized use or appropriation of patented or copyrighted material, ideas, etc

n.early 15c., from Medieval Latin piratia, from Greek peirateia “piracy,” from peirates (see pirate (n.)).