a person with a mistrustful attitude to accepted opinions
a person who doubts basic religious principles, e.g. eternal life and divine guidance; an atheist
in philosophy, somebody who denies the possibility of absolute knowledge, believing that even the most rigorous enquiry can only lead to an approximation of certainty
sceptical adj
sceptically adv
scepticism /-siz(ə)m/ noun
[via Latin from Greek skeptikos, from skepsis enquiry or doubt]