1. (a.) Sound in opinion or doctrine, especially in accepted religious doctrine\; hence, holding the Christian faith; believing the doctrines taught in the Scriptures; -- opposed to heretical and heterodox; as, an orthodox Christian.

2. (a.) According or congruous with the doctrines of Scripture, the creed of a church, the decree of a council, or the like; as, an orthodox opinion, book, etc.

3. (a.) Approved; conventional.

Christian Orthodox Jew Sunni Muslim accepted accordant accustomed acknowledged admitted anal approved authentic authoritative authorized being done bourgeois button-down canonical canonist comme il faut common compulsive concordant conformable conformist conservative conventional correct corresponding customary de rigueur decent decorous die-hard doctrinal dour established evangelical faithful firm fogyish formal formalistic fundamentalist hard harmonious hidebound impliable in accord in keeping in line in step inexorable inflexible iron ironbound ironclad ironhanded kosher literal meet muscle-bound obdurate obstinate of the faith official old-line ordinary orthodox Christian orthodoxical orthodoxist pedantic plastic popular precisianistic prevailing prevalent procrustean proper purist puristic puritan puritanic reactionary received recognized regular relentless right rigid rigorist rigoristic rigorous rockbound sanctioned scriptural seemly sound square standard stiff straight straightlaced straitlaced stubborn stuffy textual textualist textuary the orthodox tory traditional traditionalist traditionalistic TRUE true believer true-blue unbending uncompromising unrelenting unyielding uptight