cynic >> /ˈsɪnɪk/
Definition: [noun] A person who believes that people are motivated purely by self-interest rather than acting for honorable or unselfish reasons.
Example: some cynics thought that the controversy was all a publicity stunt
Definition: [noun] A member of a school of ancient Greek philosophers founded by Antisthenes, marked by an ostentatious contempt for ease and pleasure. The movement flourished in the 3rd century BC and revived in the 1st century AD.
Example: The most extensive ancient report about the Cynics is found in Diogenes Laertius, Lives of the Philosophers, Book 6, although he is not a reliable source.