orth-

combining form

variants or ortho-
1
: straight : upright : vertical
orthograde
2
: perpendicular
orthorhombic
3
: correct : corrective
orthodontia
4
a
: hydrated or hydroxylated to the highest degree
orthophosphoric acid
b
: involving substitution at or characterized by or having the relationship of two neighboring positions in the benzene ring
ortho-xylene

Word History

Etymology

Greek, from orthos straight, right, true; akin to Sanskrit ūrdhva high, upright

Dictionary Entries Near orth-

ortet

orth-

orthal

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Cite this Entry

“Orth-.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/orth-. Accessed 22 Nov. 2024.

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Medical Definition

orth-

prefix
variants or ortho-
1
: hydrated or hydroxylated to the highest degree
orthophosphoric acid
2
: involving substitution at or characterized by or having the relationship of two neighboring positions in the benzene ring
—abbreviation o-
ortho-xylene or o-xylene
 compare meta- sense 2, para- sense 2
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