combining form
or ortho-
Etymology: Middle English, from Middle French, straight, right, true, from Latin, from Greek, from orthos; akin to Gothic ga wrisqan to bring fruit, Sanskrit ūrdhva upright, high, vardhate he increases
1.
a. : straight : upright : vertical
ortho ceras
orth al
ortho grade
ortho symmetric
b. : exact : parallel
ortho diagram
ortho -cousin
ortho dome
2. : correct : corrective
orth ometry
orth odontia
3.
a. : an acid in the highest hydrated or hydroxylated form known either in the free state or in salts or esters
ortho arsenic acid
ortho formic acid
— compare meta- 4 c, pyr- 2a
b.
(1) : the relation of two neighboring positions in the benzene ring
(2) ortho- , usually italic : a derivative in which two substituting groups occupy such positions — abbr. o-
ortho -xylene or o -xylene is 1,2-dimethyl-benzene
— compare meta- 4b, para- 2b
4. : derived from igneous rock — in the name of a metamorphic rock
ortho gneiss
ortho site
— compare para-