pi·rate 
(pīrĭt)
(pīrĭt)n.
1. One who commits or practices piracy at sea.
2. One who makes use of or reproduces the work of another without authorization.
3. One who illegally intercepts or uses radio or television signals, especially one who operates an illegal television or radio station.
v. pi·rat·ed, pi·rat·ing, pi·rates
v.tr.
1. To attack and rob (a ship at sea).
2. To take (something) by piracy.
3. To make use of or reproduce (another's work) without authorization.
v.intr.
To act as a pirate; practice piracy.
[Middle English, from Old French, from Latin pīrāta, from Greek peirātēs, from peirān, to attempt, from peira, trial; see per-3 in the Appendix of Indo-European roots.]
pi·ratic (pī-rătĭk), pi·rati·cal (-ĭ-kəl) adj.
pi·rati·cal·ly adv.