ortho-

1 definition found

ortho- - Collaborative International Dictionary of English v.0.48 :

  Ortho- \Or"tho-\ ([^o]r"th[-o]-) pref. [Gr. 'orqo`s straight;
     akin to Skr. [=u]rdhva upright, v[.r]dh to grow, to cause to
     grow.]
     [1913 Webster]
     1. A combining form signifying straight, right, upright,
        correct, regular; as, orthodromy, orthodiagonal, orthodox,
        orthographic.
        [1913 Webster]
  
     2. (Chem.) 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.) 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.
            [1913 Webster]
  
     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.
           [1913 Webster]