Stories We Like: A Guide to the Comma
ortho- or orth-
Straight; upright; vertical: orthotropic.
Correct; correction: orthopsychiatry.
Hydrated form of an acid or of its salts: orthoboric acid.
Diatomic molecules in which the nuclei have the same direction of spin: orthohydrogen.
Abbr. o- Of or relating to one of three possible isomers of a benzene ring with adjacent carbon atoms having attached chemical groups. Usually used in italic: ortho-dibromobenzene.