A person hired to fight for another country than their own; SYN. soldier of fortune.
Soldier hired by the army of another country or by a private army. Mercenary military service originated in the 14th century, when cash payment on a regular basis was the only means of guaranteeing soldiers' loyalty. In the 20th century mercenaries have been common in wars and guerrilla activity in Asia, Africa, and Latin America.
Most famous of the mercenary armies was the Great Company of the 14th century, which was in effect a glorified protection racket, comprising some 10,000 knights of all nationalities and employing condottieri, or contractors, to serve the highest bidder. By the end of the 14th century, condottieri and freelances were an institutionalized aspect of warfare. In the 18th century, Swiss cantons and some German states regularly provided the French with troops for mercenary service as a means of raising money; they were regarded as the best forces in the French army. Britain employed 20,000 German mercenaries to make up its numbers during the Seven Years’ War 1756–63 and used Hessian forces during the American Revolution 1775–83.
Article 47 of the 1977 Additional Protocols to the Geneva Convention stipulates that “a mercenary shall not have the right to be a combatant or a prisoner of war” but leaves a party to the Protocols the freedom to grant such status if so wished.

ETYM Old Eng. mercenarie, French mercenaire, from Latin mercenarius, from merces wages, reward. Related to Mercy.
Used of soldiers hired by a foreign army; SYN. freelance.