noun, masculine/feminine/ɔʁ.to/plural: orthos
a spelling (of a word); an orthodontist; a speech therapist; an idiot, a retard; an orthoscopic eyepiece
“Désolée pour la faute d'ortho.” — Sorry for the spelling error.
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.