the.com/cynic

means A person who distrusts stated motives and expects the worst of people's intentions, often as a defense against disappointment.

from From Greek 'kynikos,' meaning 'dog-like,' tied to the ancient Cynic philosophers who followed Diogenes. They scorned wealth, convention, and social niceties, living as austerely and shamelessly as dogs — some say the name came from the Kynosarges gymnasium where they gathered, others that it mocked their blunt, 'doggish' behavior in public. Over centuries the word drifted from a philosophy of radical honesty and simplicity to its modern sense: someone who sneers at sincerity and assumes the worst, a meaning the original Cynics would likely have found both ironic and a little insulting.