ortho

¹

[ awr-thoh ]

adjective

, Chemistry.

1. pertaining to or occupying two adjacent positions in the benzene ring. Compare meta ³, para ³.

ortho-

²

1. a combining form occurring in loanwords from Greek, where it meant “straight,” “upright,” “right,” “correct” ( orthodox ) and on this model used in the formation of compound words ( orthopedic ).
2. Chemistry.
   1. a combining form used in the name of that acid in a given series of acids that contains the most water ( orthoboric acid ). Compare meta-, pyro-.
   2. a combining form used in the names of the salts of these acids: if the acid ends in -ic, the corresponding salt ends in -ate ( orthoboric acid (H 3 BO 3 ) and potassium orthoborate (K 3 BO 3 )); if the acid ends in -ous, the corresponding salt ends in -ite ( orthoantimonous acid (H 3 SbO 3 ) and potassium orthoantimonite (K 3 SbO 3 )).

ortho-

combining_form

1. straight or upright

   orthotropous

2. perpendicular or at right angles

   orthoclastic

3. correct or right

   orthography

   orthodontics

   orthodox

   orthoptics

4. See oarsman
   often in italics denoting an organic compound containing a benzene ring with substituents attached to adjacent carbon atoms (the 1,2- positions) o- Compare oarsman Compare oarsman

   orthodinitrobenzene

5. See meta-
   denoting an oxyacid regarded as the highest hydrated form of the anhydride or a salt of such an acid See meta-

   orthophosphoric acid

6. See para-
   denoting a diatomic substance in which the spins of the two atoms are parallel See para- 1

   orthohydrogen

Word History and Origins

Origin of ortho¹

First recorded in 1875–80; independent use of ortho-

Origin of ortho²

< Greek, combining form of orthós straight, upright, correct

Word History and Origins

Origin of ortho¹

from Greek orthos straight, right, upright

Example Sentences

Ortho Sol makes precision screws for the most delicate of construction projects: spinal fusion.

From The Daily Beast

And also those that contain norgestimate, which include Ortho-Cyclen and Tri-Cyclen.

From The Daily Beast

The influence of position of an alkyl in the aromatic bodies is well shown in ortho-, para- and meta-derivatives.

From Project Gutenberg

The ortho molecules rotate with odd rotational quantum numbers, while the para molecules rotate with even quantum numbers.

From Project Gutenberg

This block is of the ortho-cerite stratum of Drummond Island.

From Project Gutenberg

This substance readily yields ortho-oxybenzoic acid or salicylic acid, which on nitration yields two mononitro-oxybenzoic acids.

From Project Gutenberg

It is well known that di-ortho-substituted benzoic acids are esterified with difficulty.

From Project Gutenberg