a person who questions the validity or authenticity of something purporting to be factual.

a person who maintains a doubting attitude, as toward values, plans, statements, or the character of others.

a person who doubts the truth of a religion, esp. Christianity, or of important elements of it.

( initial capital letter ) Philosophy .

a member of a philosophical school of ancient Greece, the earliest group of which consisted of Pyrrho and his followers, who maintained that real knowledge of things is impossible.

any later thinker who doubts or questions the possibility of real knowledge of any kind.

pertaining to skeptics or skepticism; skeptical.

( initial capital letter ) pertaining to the Skeptics.

noun

believer , devotee , disciple

noun

agnostic , apostate , atheist , cynic , disbeliever , dissenter , doubter , doubting thomas * , freethinker , heathen , heretic , infidel , materialist , misanthrope , misbeliever , nihilist , pagan , pessimist , profaner , questioner , rationalist , scoffer , unbelievernotes:cynics doubt because they question motives (cynic was first a school of philosophy expressing contempt for wealth and pleasure; the word cynic comes from greek cyniko \'doglike\'); skeptics doubt reports of what they hear or read , doubting thomas , nonbeliever , unbeliever , sceptic