Main Entry: orth-

Variant(s): or ortho-

Function: combining form

Etymology: Greek, from orthos straight, right, true; akin to Sanskrit ūrdhva high, upright

1 : straight : upright : vertical <orthograde>
2 : perpendicular <orthorhombic>
3 : correct : corrective <orthodontia>
4 a : hydrated or hydroxylated to the highest degree <orthophosphoric acid> b : involving substitution at or characterized by or having the relationship of two neighboring positions in the benzene ring <ortho-xylene>