ortho- medical definition

or orth-

1. Straight; upright; vertical: orthotropic.
2. Correct; correction: orthopsychiatry.
3. Hydrated form of an acid or of its salts: orthoboric acid.
4. Diatomic molecules in which the nuclei have the same direction of spin: orthohydrogen.
5. Abbr. o- Of or relating to one of three possible isomers of a benzene ring with adjacent carbon atoms having attached chemical groups: ortho-dibromobenzene.