cynic

noun

1. a member of a school of ancient Greek philosophers who held virtue to be the only good and stressed independence from worldly needs and pleasures: they became critical of the rest of society and its material interests
2. a cynical person

Etymology: L Cynicus < Gr kynikos, lit., doglike, as if < kyōn, dog (see hound), nickname of Diogenes, but prob. in allusion to the Kynosarges, a gymnasium where the Cynics taught (< kyōn + argos, lit., white dog, so named after an animal in a myth concerning Hercules, to whom the gymnasium was sacred)

adjective

1. of or like the Cynics or their doctrines
2. cynical