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>