1. A murderer, especially one who cuts throats.
2. An unprincipled, ruthless person.
3. A cutthroat trout.

1. Cruel; murderous.
2. Relentless or merciless in competition: a cutthroat business.
3. Sports & Games. Being a form of a game in which each of three or more players acts and scores individually: cutthroat handball; cutthroat bridge.

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.