of, pertaining to, or conforming to the approved form of any doctrine, philosophy, ideology, etc.
2.
of, pertaining to, or conforming to beliefs, attitudes, or modes of conduct that are generally approved.
3.
customary or conventional, as a means or method; established.
4.
sound or correct in opinion or doctrine, especially theological or religious doctrine.
5.
conforming to the Christian faith as represented in the creeds of the early church.
6.
( initial capital letter ) of, pertaining to, or designating the Eastern Church, especially the Greek Orthodox Church.
7.
( initial capital letter ) of, pertaining to, or characteristic of Orthodox Jews or Orthodox Judaism.
Origin: 1575–85; < Late Latinorthodoxus right in religion < Late Greekorthódoxos, equivalent to ortho-ortho- + dóx(a) belief, opinion + -os adj. suffix
1580s, from L.L. orthodoxus, from Gk. orthodoxos "having the right opinion," from orthos "right, true, straight" (see ortho-) + doxa "opinion, praise," from dokein "to seem," from PIE base *dek- "to take, accept" (see decent). As the name of the
Eastern Church, first recorded in Eng. 1772; in the sense of branch of Judaism, first recorded 1853.