conforming to established, dominant, or official doctrine, e.g. in religion

‘Do you know where the wicked go after death?’ ‘They go to hell,’ was my ready and orthodox answer — Charlotte Brontë

in accordance with proper practice; conventional

It points also to an orthodox burial with proper accompaniment of medical certificate and official sanction — Conan Doyle

(Orthodox) of or denotingrelating or belonging to any of the Eastern Churches headed by the patriarch of Constantinople that separated from the Western Church in the eleventh cent. and have characteristic doctrines, liturgy, and forms of organization

the Greek Orthodox Church

(usu Orthodox) of or denoting being Judaism that keeps to strict and traditional interpretation of the Torah (Jewish scripture) and authoritative rabbinic tradition

an Orthodox Jew