mercenary

American Heritage® Dictionary of the English Language, Fourth Edition

1. adj. Motivated solely by a desire for monetary or material gain.
2. adj. Hired for service in a foreign army.
3. n. One who serves or works merely for monetary gain; a hireling.
4. n. A professional soldier hired for service in a foreign army.

Century Dictionary and Cyclopedia

1. Working or acting for reward; hired; serving only for gain; selling one's services to the highest bidder.
2. Hence Venal; sordid; actuated only by hope of reward; ready to accept dishonorable gain: as, a mercenary prince or judge; a mercenary disposition.
3. Pertaining or due to hope of gain or reward; done, given, etc., in return for hire; resulting from sordid motives: as, mercenary services; a mercenary act.
4. Synonyms Hireling, etc. See venal.
5. n. A person who works for pay: especially, one who has no higher motive to work than love of gain.
6. n. Specifically, a soldier in foreign service; a professional soldier. This term became common during the long wars of the years immediately following the middle ages, when professional soldiers who served any one who would pay them were contrasted with those who still followed their feudal superiors.

Wiktionary

1. adj. Motivated by private gain.
2. n. A person employed to fight in an armed conflict who is not a member of the state or military group for which they are fighting and whose prime or sole motivation is private gain.

GNU Webster's 1913

1. adj. Acting for reward; serving for pay; paid; hired; hireling; venal.
2. adj. Moved primarily by considerations of pay or profit; greedy of gain; sordid; selfish.
3. n. One who is hired; a hireling; especially, a soldier hired into foreign service.

WordNet 3.0

1. adj. serving for wages in a foreign army
2. adj. profit oriented
3. adj. marked by materialism
4. n. a person hired to fight for another country than their own