Green’s Dictionary of Slang

1. a prison [abbr. SE quadrangle].

1864, 1867, 1870		Hotten Sl. Dict.
1937–84		Partridge DSUE (1984) 944/2: [...] late C.18–20.
2001		D. Looser Boobslang [U. Canterbury D.Phil. thesis] 150/1: quad (also quod) n. a prison.

2. a horse [SE quadriped].

1843		R.S. Surtees Handley Cross (1854) 113: Lend me your quad a minute to go and catch mine upon.
1876		H.E. Malet Annals of the Road 90: [N]o pains or expense were spared to collect the best of quads and to render the thing complete.
1885		Eng. Illus. Mag. April 509: The second rider... got his gallant quad over, and... went round the course alone [F&H].
1889		Dead Bird (Sydney) 17 Aug. 6/4: The mount perforce sat down, so did the major, but a little in the rear of his quad.
1891		F.W. Carew Autobiog. of a Gipsey 416: I cuts the quad under the shoulder with the flail.
1894		J. Astley Fifty Years (2nd edn) I 97: He was mounted upon a sorry old quad.

3. a quadricycle.

1984

Partridge DSUE (8th edn) 944/2: 1888.

4. (US campus) a very clumsy person [? f. quadriplegic].

1977		Eble Campus Sl. Apr. 3: quad – clumsy, stupid person.
1996		Eble Sl. and Sociability 59: Three geometric terms – straight, square, and quad – are all are derogatory epithets that designate with various connatations ‘a person who does not fit in with the prevailing college life style’.
1997–2002		Alt. Eng. Dict. 🌐 quad (noun) A very clumsy person. Often used amongst friends when one makes an embarrasing [sic] play during a sports match, e.g. missing a penalty kick, missing the backboard, etc.

5. (US drugs) methaqualone [brandname Quaalude].

1973		Time 5 Mar. 73: On the street and on campus, methaqualone is known by various corruptions of its trade names: ‘quads’.
1976		N. Thornburg Cutter and Bone (2001) 17: Her smile was heedless, stoned [...] ‘Don’t tell me, let me guess. Quads and vodka.’.
1981		D.E. Miller Bk of Jargon 338: quads: (Quaaludes: Methaqualone).
2001		ONDCP Street Terms 17: Quads — Depressants.

6. a quadriplegic.

1990

S. Morgan Homeboy 109: The quad leaned his strawthatched head to the match Joe held.

7. see quod n. (1)