Orthodoxy The word orthodox, from Greek orthodoxos "having the right opinion," from orthos ("right, true, straight") + doxa ("opinion, praise", related to dokein, "thinking"), is typically used to mean adhering to the accepted or traditional and established faith, especially in religion.The term did not conventionally exist with any degree of formality (in the sense in which it is now used) prior to the advent of Christianity in the Greek-speaking world, though the word does occasionally show up in ancient literature in other, somewhat similar contexts.