Emily Dickinson Lexicon

HER'E-TIC, n. [Gr. αιρετικος; It. eretico; Fr. heretique.]

1. A person under any religion, but particularly the Christian, who holds and teaches opinions repugnant to the established faith, or that which is made the standard of orthodoxy. In strictness, among Christians, a person who holds and avows religious opinions contrary to the doctrines of Scripture, the only rule of faith and practice.
2. Any one who maintains erroneous opinions. Shak.