ortho

Ultimately from the prefix ortho-.

• (Received Pronunciation) IPA^(key): /ˈɔː.θəʊ/
• (General American) IPA^(key): /ˈoɹ.θoʊ/
• Rhymes: -ɔː(ɹ)θəʊ
• Hyphenation: or‧tho

ortho (countable and uncountable, plural orthos)

1. (countable, chemistry) An isomer of a benzene derivative having two substituents adjacent on the ring.
   • 1887 December 21, Thomas M. Morgan, “On Some Derivatives of Ortho-Nitro-Cinnamic Acid”, in Chemical News‎^[269]:

     When the cinnamic acid had been nitrated the ortho was separated from the para, by suspending in alcohol and leading hydrochloric acid gas into the mixture : […] .

   • 2009 February 27, P. Neumann et al., “Response to Comment on "Multipartite Entanglement Among Single Spins in Diamond"”, in Science‎^[1], volume 323, number 5918, →DOI:

     Similarly, it also does not make sense to call the spin states of ortho and para hydrogen entangled.

2. (countable, astronomy) A certain type of flat eyepiece.
   • 1998, Terence Dickinson, NightWatch: A Practical Guide to Viewing the Universe, page 76:

     Orthos are excellent eyepieces, still preferred by some backyard astronomers for medium- and high-power applications, especially planetary observing.

3. (countable, photography, dated) An orthochromatic plate.
   • 1908 June, Charles F. Rice, “On the Use of Orthochromatic Plates”, in Photographic Times, page 174:

     Wherever the exposure is likely to be cut short— and this includes all high speed work and most portraiture — the ortho is not so suitable as the ordinary plate.

4. (countable, linguistics) Clipping of orthography.
5. (countable, photography) Clipping of orthophoto.
   • 2001, Drew Decker, GIS Data Sources, page 105:

     The typical orthophoto building process is a long one, however, and the photography that the orthos are based may be several years old before an orthophoto is ready for distribution.

6. (uncountable, medicine) Clipping of orthopedics.

• Rooth, thoro

• IPA^(key): /ˈɔr.toː/
• Rhymes: -ɔrtoː
• Hyphenation: or‧tho

ortho c (plural ortho's, diminutive orthootje n)

1. (informal) clipping of orthodontist or orthodontiste

clipping of words beginning with ortho-

(4) The pejorative use of the term is from orthopédagogue (a kind of teacher assigned to students having difficulties) which came, by association, to designate people requiring such services.

• IPA^(key): /ɔʁ.to/

ortho m or f by sense (plural orthos)

1. a spelling (of a word)

   Désolée pour la faute d'ortho.

   Sorry for the spelling error.

2. an orthodontist
3. a speech therapist
4. (Quebec, offensive) an idiot, a retard

   Criss d'ortho!^[1]

   Fucking retard!

   • 2019, Patrick Nicol, Les Manifestations, page 317:

     La police est venue, ce qu’elles ont fait était assez grave pour mériter quelques périodes de congé. Même les gars, et même les orthos, les considèrent maintenant avec respect, surtout qu’elles n’ont pas trahi leur secret.

     The police came, what they did was serious to warrant a few periods of leave. Even the guys, & the fuckwits, now treated them with respect, especially because they hadn't betrayed their secret.

5. (medicine) an orthoscopic eyepiece

• “ortho”, in Trésor de la langue française informatisé [Digitized Treasury of the French Language], 2012.