Green’s Dictionary of Slang

(orig. US) derog. ref. to a mentally retarded person, whether actually or fig; also as adj.

1967–8		Baker et al. CUSS 184: Retard – A person who always does the wrong thing. A person without much social or academic ability.
1972		T.C. Bambara ‘The Lesson’ in Gorilla, My Love (1972) 88: Miss Moore asking us do we know what money is, like we a bunch of retards.
1979		D. Gram Foxes (1980) 17: We’re going to school, retardo.
1981		J. Ellroy Brown’s Requiem 190: For treating me like a slave! Like a retardo!
1983		S. King Christine 247: You can laugh, you retard.
1990		R. Campbell Sweet La-La Land (1999) 218: He’s this retard used to hang around Bitsy.
2001		J. Stahl Plainclothes Naked (2002) 207: You think ’cause I’m part Rican, I’m some retardo punk?
2006		G. Iles Turning Angel 162: I’m not sure why I tried out except that it’s what you’re supposed to do. I’m such a retard.
2011		S. Kelman Pigeon English 60: Don’t be a retard, you can’t just ask for it straight out.
2016		Dly Pennsylvanian 23 Mar. 🌐 Other words like ‘retard’ fall under the same category of words with troubling connotations that we casually use.