1. skeptic The skeptic doubts divine revelation; the disbeliever and the unbeliever reject it, the disbeliever with more of intellectual dissent, the unbeliever (in the common acceptation) with indiff Synonyms: skeptic, agnostic, deist, doubter, infidel, unbeliever, atheist, disbeliever, freethinker Antonyms: believer, Christian