"correctness of opinion," especially in theology; "conformity to the Church creeds," 1620s, from French orthodoxie and directly from Late Latin orthodoxia, from late Greek orthodoxia "right opinion," abstract noun from orthodoxos "having the right opinion" (see orthodox). Orthodoxies "correct belief or opinion" is by 1871.
1660s, in reference to a type of perspective in drawings, etc., from ortho- "true, correct" + -graphic "of or pertaining to drawing" (see graphic (adj.)). Meaning "belonging to the writing of words with proper letters, relating to the spelling of words" is by 1868, from orthography + -ic. Related: Orthographically (used from 1610s in reference to spelling).
mid-15c., in reference to theological opinions or faith, "what is regarded as true or correct," 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").
Of other subjects than religion or theology from 1640s. Meaning "of or pertaining to the Greek Church," by 1772. As a noun, "member of the Eastern Orthodox Church, from 1580s. In reference to a branch of Judaism, recorded from 1853; as a noun meaning "an Orthodox Jew," by 1889.
before vowels orth-, word-forming element meaning "straight, upright, rectangular, regular; true, correct, proper," now mostly in scientific and technical compounds, from Greek orthos "straight, true, correct, regular," from PIE *eredh- "high" (source also of Sanskrit urdhvah "high, lofty, steep," Latin arduus "high, steep," Old Irish ard "high").
mid-15c., ortographie, ortografie, "branch of knowledge concerned with correct or proper spelling," from Old French ortografie (13c.), from Latin orthographia, from Greek orthographia "correct writing," from orthos "correct" (see ortho-) + root of graphein "to write" (see -graphy.
The classical spelling was restored in English and French (orthographie) in early 16c. The meaning "branch of language study which treats of the nature and properties of letters" is from 1580s. An early 15c. glossary has ryght wrytynge as translation of ortographia. Related: Orthographer.
"relating to or concerned with the cure of bodily deformities in children or in persons generally," 1840, from French orthopédique, from orthopédie, coined by French physician Nicholas Andry (1658-1742), from Greek orthos "straight, correct" (see ortho-) + paideia "rearing of children," from pais (genitive paidos) "child" (see pedo-).