ortho

[ awr-thoh ]

/ ˈɔr θoʊ /

adjective Chemistry.

pertaining to or occupying two adjacent positions in the benzene ring.Compare meta², para³.

Nearby words

orth., orthergasia, orthesis, orthetics, orthicon, ortho, ortho-, ortho-cousin, ortho-dichlorobenzene, ortho-kung t cell, ortho-nitrophenol

Origin of ortho

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

Definition for ortho (2 of 2)

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).

Chemistry.

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-.
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 (H3BO3) and potassium orthoborate (K3BO3)); if the acid ends in -ous, the corresponding salt ends in -ite (orthoantimonous acid (H3SbO3) and potassium orthoantimonite (K3SbO3)).

Also especially before a vowel, orth-.

Origin of ortho-

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

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for ortho

Ortho Sol makes precision screws for the most delicate of construction projects: spinal fusion.
Patients Screwed in Spine Surgery ‘Scam’|The Center for Investigative Reporting|November 3, 2014|DAILY BEAST
Mr. Tal- mage, true to the fawning, cringing spirit of ortho- doxy, lauds the living queen and cruelly maligns the genius dead.
The Works of Robert G. Ingersoll, Vol. 5 (of 12)|Robert G. Ingersoll
The influence of position of an alkyl in the aromatic bodies is well shown in ortho-, para- and meta-derivatives.
Poisons: Their Effects and Detection|Alexander Wynter Blyth
This change only occurs when the halogen atom is in the ortho- or para- position to the -N2- group.
Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 4|Various

The ortho- and para-nitro-benzoic acids can be obtained by oxidizing ortho-and para-nitro-cinnamic acids.
Encyclopaedia Britannica, 11th Edition, Volume 3, Slice 6|Various
The ortho molecules rotate with odd rotational quantum numbers, while the para molecules rotate with even quantum numbers.
Unwise Child|Gordon Randall Garrett

British Dictionary definitions for ortho

ortho-

before a vowel orth-

combining form

straight or uprightorthotropous

perpendicular or at right anglesorthoclastic

correct or rightorthodontics; orthodox; orthography; orthoptics

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

denoting an oxyacid regarded as the highest hydrated form of the anhydride or a salt of such an acidorthophosphoric acid See meta- (def. 6)

denoting a diatomic substance in which the spins of the two atoms are parallelorthohydrogen See para- 1 (def. 8)

Word Origin for ortho-

from Greek orthos straight, right, upright

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for ortho

ortho-

before vowels orth-, word-forming element meaning "straight, upright, rectangular, regular; true, correct, proper," now mostly in scientific and technical compounds, from Greek ortho-, stem of orthos "straight, true, correct, regular," from PIE *eredh- "high" (cf. Sanskrit urdhvah "high, lofty, steep," Latin arduus "high, steep," Old Irish ard "high").

Medicine definitions for ortho

ortho-

pref.

Straight; upright; vertical:orthotropic.

Correct; correction:orthopsychiatry.

Hydrated form of an acid or of its salts:orthoboric acid.

Diatomic molecules in which the nuclei have the same direction of spin:orthohydrogen.

Of or relating to one of three possible isomers of a benzene ring with adjacent carbon atoms having attached chemical groups:ortho-dibromobenzene.