mid-15c., of opinions, faith, from Late Latin orthodoxus, from Greek orthodoxos "having the right opinion," from orthos "right, true, straight" (see ortho-) + doxa "opinion, praise," from dokein "to seem," from PIE root *dek- "to take, accept" (see decent). As the name of the Eastern Church, first recorded in English 1772; in reference to a branch of Judaism, first recorded 1853.