adjective

1. conforming to the usual beliefs or established doctrines, as in religion, politics, etc.; approved or conventional [orthodox ideas]; specif.,
   1. conforming to the Christian faith as formulated in the early ecumenical creeds and confessions
   2. strictly conforming to the rites and traditions of Judaism, such as kashrut, the Sabbath, etc., as formulated by the Torah and Talmud
2. designating or of any of the churches comprised in the Eastern Orthodox Church

Etymology: < Fr or LL: Fr orthodoxe < LL orthōdoxus < LGr(Ec) orthodoxos, orthodox (in religion) < Gr orthos (see ortho-) + doxa, opinion < dokein, to think: see decent