ortho-


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Related to ortho-: Ortho k, Ortho Evra

ortho-

(word root) straight
Examples of words with the root ortho-: orthodontia
Abused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embree

ortho-

or orth-
pref.
1. Straight; upright; vertical: orthotropous.
2. Perpendicular: orthorhombic.
3. Correct; correction: orthopsychiatry.
4. The most fully hydrated form of an acid or of its salts: orthoboric acid.
5. Of or relating to one of three possible isomers of a benzene ring with two attached chemical groups in which the carbon atoms with attached groups are adjacent: ortho-dibromobenzene.

[Middle English, from Old French, from Latin, from Greek, from orthos, straight, correct, right.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

ortho-

or before a vowel

orth-

combining form
1. straight or upright: orthotropous.
2. perpendicular or at right angles: orthoclastic.
3. correct or right: orthodontics; orthodox; orthography; orthoptics.
4. (Chemistry) (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 meta-4 Compare para-16
5. (Chemistry) denoting an oxyacid regarded as the highest hydrated form of the anhydride or a salt of such an acid: orthophosphoric acid. See meta-6
6. (Chemistry) denoting a diatomic substance in which the spins of the two atoms are parallel: orthohydrogen. See para-18
[from Greek orthos straight, right, upright]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

or•tho

(ˈɔr θoʊ)

adj.
pertaining to or occupying two adjacent positions in the benzene ring. Compare meta, para 2.
[1875–80; independent use of ortho-]

ortho-

1. a combining form meaning “straight,” “upright,” “right,” “correct”: orthodontics; orthopedic.
2.
a. a combining form used in the name of the most hydrated acid in a given series: orthoboric acid. Compare meta- (def. 2a), pyro- (def. 2a).
b. a combining form used in the names of benzene derivatives in which the substituting group occupies the ortho position in the benzene ring.
Also, esp. before a vowel, orth-.
[< Greek, comb. form of orthós straight, upright, correct]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
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