Category:Ortho-

Or"tho-. Etym: [gr. upright, vrdh to grow, to cause to grow.]

1. A combining form signifying straight, right, upright, correct, Regular; as, orthodromy, orthodiagonal, orthodox, orthographic.

2. (chem.)

Defn: a combining form (also used adjectively), designating: (a) (inorganic chem.) The one of several acids of the same element (as the phosphoric acids), which actually occurs with the greatest Number of hydroxyl groups; as, orthophosphoric acid. Cf. Normal. (b) (organic chem.)

Defn: connection with, or affinity to, one variety of isomerism, Characteristic of the benzene compounds; -- contrasted with meta- or Para-; as, the ortho position; hence, designating any substance Showing such isomerism; as, an ortho compound.

Note: in the graphic representation of the benzene nucleus (see Benzene nucleus, under benzene), provisionally adopted, any substance Exhibiting double substitution in adjacent and contiguous carbon Atoms, as 1 & 2, 3 & 4, 4 & 5, etc., is designated by ortho-; as, Orthoxylene; any substance exhibiting substitution of two carbon Atoms with one intervening, as 1 & 3, 2 & 4, 3 & 5, 4 & 6, etc., by Meta-; as, resorcin or metaxylene; any substance exhibiting Substitution in opposite parts, as 1 & 4, 2 & 5, 3 & 6, by para-; as, Hydroquinone or paraxylene.