noun, plural pi·ra·cies.
- practice of a pirate; robbery or illegal violence at sea.
- the unauthorized reproduction or use of a copyrighted book, recording, television program, patented invention, trademarked product, etc.: The record industry is beset with piracy.
- Also called stream capture. Geology. diversion of the upper part of one stream by the headward growth of another.
noun plural -cies
- British robbery on the seas within admiralty jurisdiction
- a felony, such as robbery or hijacking, committed aboard a ship or aircraft
- 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.)).