Merriam-Webster Collegiate Dictionary - cynic

 noun  Etymology: Middle French or Latin, Middle French cynique, from Latin ~us, from Greek kynikos, literally, like a dog, from kyn-, kyon dog — more at hound  Date: 1542  1. capitalized an adherent of an ancient Greek school of philosophers who held the view that virtue is the only good and that its essence lies in self-control and independence  2. a faultfinding captious critic; especially one who believes that human conduct is motivated wholly by self-interest  • ~ adjective