a person who doubts the existence of human sincerity or of any motive other than self-interest
‘What is a cynic?’ ‘A man who knows the price of everything and the value of nothing’ — Oscar Wilde
a person who is habitually pessimistic or sardonic
(Cynic) an adherent of an ancient Greek school of philosophers who held that virtue is the highest good and that its essence lies in masteringy over one's desires and wants
The Cynics of ancient Greece, among whom Diogenes is most famous, taught that the only way to attain peace of mind is to reject the ordinary amenities of life and to live simply and austerely. It is probably because they disdained all conventions and attempted to live naturally, like animals, that they were called ‘cynic’, literally ‘doglike’ — Dr Anthony Grayling
cynical adj
cynically adv
cynicism /-siz(ə)m/ noun
[early French cynique via Latin from Greek kynikos, literally ‘like a dog’ from kyn-, kyōn dog, which became a nickname for a Cynic]