c. 1300 (mid-13c. as a surname), "a sea-robber, sea-plunderer, one who without authority and by violence seizes or interferes with the ship or property of another on the sea," especially one who is habitually engaged in such robbery or sails the seas for the robbery and plunder of merchant vessels, from Old French pirate and directly from Medieval Latin pirata "sailor, corsair, sea robber" (source also of Spanish, Italian pirata, Dutch piraat, German Pirat), from classical Latin, from Greek peiratēs "brigand, pirate," literally "one who attacks" (ships), from peiran "to attack, make a hostile attempt on, try," from peira "trial, an attempt, attack" (from PIE *per-ya-, suffixed form of root *per- (3) "to try, risk").
An Old English word for it was sæsceaða ("sea-scather"); a pirate-ship was a ðeofscip ("thief-ship"). Figurative sense of "plunderer, despoiler" is from late 15c. Meaning "one who takes another's work without permission" first recorded 1701; sense of "unlicensed radio broadcaster" (generally transmitting from a ship outside territorial waters) is from 1913.
"to rob on the high seas; commit piracy upon," 1570s, from pirate (n.). By 1706 as "appropriate and reproduce the literary or artistic work of another without right or permission; infringe on the copyright of another." Related: Pirated; pirating.
early 15c., "robbery upon the sea, the practice of robbing on the high seas," from Medieval Latin piratia, from classical Latin, Greek peirateia "piracy," from peiratēs "brigand, pirate" (see pirate (n.)).
Specifically, in the law of nations, the crime of depredations or wilful and aggressive destruction of life or property committed on the seas by persons having no commission or authority from any established state. As commonly used it implies something more than a simple theft with violence at sea, and includes something of the idea of general hostility to law. According to the opinion of some, it implies only unlawful interference with a vessel ; according to others, it includes also depredations on the coast by a force landing from the sea. [Century Dictionary]
Proto-Indo-European root meaning "to try, risk," an extended sense from root *per- (1) "forward," via the notion of "to lead across, press forward."
It is the hypothetical source of/evidence for its existence is provided by: Latin experiri "to try," periculum "trial, risk, danger;" Greek peira "trial, attempt, experience," empeiros "experienced;" Old Irish aire "vigilance;" Old English fær "calamity, sudden danger, peril, sudden attack," German Gefahr "danger," Gothic ferja "watcher.
"sea-robber, pirate," late 14c. (c. 1300 as a surname), from Middle Dutch rover "robber, predator, plunderer," especially in zeerovere "pirate," literally "sea-robber," from roven "to rob," from Middle Dutch roof "spoil, plunder," related to Old English reaf "spoil, plunder," reafian "to reave" (see reave (v.), and compare reaver).
"government-sanctioned freebooter of the seas," 1540s, from French corsaire (15c.), from Provençal cursar, Italian corsaro, from Medieval Latin cursarius "pirate," from Latin cursus "course, a running," from currere "to run" (from PIE root *kers- "to run"). The sense of the Medieval Latin verb evolved from "course" to "journey" to "expedition" to an expedition specifically for plunder. As "a privateering pirate ship" from 1630s.
The name in the languages of the Mediterranean for a privateer; chiefly applied to the cruisers of Barbary, to whose attacks the ships and coasts of the Christian countries were incessantly exposed. In English often treated as identical with pirate, though the Saracen and Turkish corsairs were authorized and recognized by their own government as part of its settled policy towards Christianity. [OED]