mercenary (adj.) Look up mercenary at Dictionary.com
1530s, from mercenary (n.), or in part from Latin mercenarius "hired, paid, serving for pay."
mercenary (n.) Look up mercenary at Dictionary.com
late 14c., "one who works only for hire," from Old French mercenaire "mercenary, hireling" (13c.) and directly from Latin mercenarius "one who does anything for pay," literally "hired, paid," from merces (genitive mercedis) "pay, reward, wages," from merx (see market (n.)).