n. Positive unbelief; the conviction that a proposition or statement for which credence is demanded is not true.n. A negation or denial of the truth of some particular thing.n. Synonyms Disbelief, Unbelief, incredulity, distrust, skepticism, infidelity. Disbelief is more commonly used to express an active mental opposition which does not imply a blameworthy disregard of evidence. Unbelief may be a simple failure to believe from lack of evidence or knowledge; but its theological use has given it also the force of wilful opposition to the truth.