(Greek: a suffix; pertaining to; of the nature of, like; in chemistry, it denotes a higher valence of the element than is expressed by -ous)
2. A person whose outlook is scornfully and often habitually negative.
A Cynic was an ancient Greek philosopher or a member of a group of ancient Greek philosophers who believed that virtue is the only good and that the only means of achieving it was through self-control. The sect was founded by Antisthenes in the 4th century B.C. From Greek kunikos and then through Latin cynicus, "dog".
These sect members had a doglike insolence, a doglike disregard for social customs, a doglike use of tubs or kennels for sleeping, and a currish insistence upon one's own opinion. It may have been a coincidence that the Greek word for "doglike" is cynikos.
The word cynic had not been in English very long before it was applied to any faultfinding critic, especially to someone who doubts the sincerity of all human motives except self-interest.