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• ortho
  ortho

  adjective

  pertaining to or occupying two adjacent positions in the benzene ring.
• ortho-
  ortho-

  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 ).

ortho

¹ American  

[awr-thoh] / ˈɔr θoʊ /

adjective

Chemistry.

1. pertaining to or occupying two adjacent positions in the benzene ring.

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ortho- ² American  

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 ).

   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 BO3 ) and potassium orthoborate (K 3 BO3 )); if the acid ends in -ous, the corresponding salt ends in -ite (orthoantimonous acid (H 3 SbO3 ) and potassium orthoantimonite (K 3 SbO3 )).

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ortho- British  

combining form

1. straight or upright

   orthotropous

2. perpendicular or at right angles

   orthoclastic

3. correct or right

   orthodontics

   orthodox

   orthography

   orthoptics

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

   orthodinitrobenzene

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

   orthophosphoric acid

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

   orthohydrogen

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Etymology

Origin of ortho¹

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

Origin of ortho-²

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

Example Sentences

In 2019, Cargle wrote an anonymous post on a live public document — called Ortho Match — that is regularly checked and updated by medical students applying to orthopedic surgery residencies.

From Los Angeles Times • Nov. 3, 2023

The medical diagnostics company is buying Ortho Clinical Diagnostics.

From Seattle Times • Dec. 23, 2021

It will change three products for roses, flowers, trees and shrubs by 2017 and other products later, said Tim Martin, vice president and general manager of Ortho, a division of Scotts Miracle-Gro.

From Washington Post • Apr. 12, 2016

I checked that with Dr. Gregory S. McDowell, the surgeon at Ortho Montana who did such a good job of fusing a burst thoracic vertebra.

From New York Times • Dec. 1, 2014

The negative was made with a Goerz Dagor lens in a Lancaster reflex upon a Seed Ortho L plate.

From Pictorial Photography in America 1921 by Pictorial Photographers of America