Green’s Dictionary of Slang

1. psychological, psychiatric; thus psycho doc, psycho ward etc.

1920		T. Thursday ‘Score Another One for Barnum’ in Argosy All-Story 11 Sept. 🌐 ‘Doc,’ he says, ‘I ain’t much on this psycho— well, what he said—stuff.’.
1927		Variety 1 June 314: [headline] Psycho drama flops. The Compagnie des Jonchets, a private club, was over its head with the psychological drama ‘Le Souffle sur la Flamme’ [OED].
1938		N. Marsh Artists in Crime 148: The psycho people say one shouldn’t repress things.
1946		J. Cary Moonlight (1995) 169: She gave you a guilty complex [...] My psycho man says that’s the worst kind.
1949		Dan Burley ‘Back Door Stuff’ 23 Apr. [synd. col.] He’s [...] crazy. Doesn’t need a wife, he needs a psycho doctor.
1951		D. Dressler Parole Chief 93: You’re jugged. Go get mugged and bugged [...] Bugged: the psycho doc studies your brain.
1953		L. Uris Battle Cry (1964) 149: If we turn you in, they’ll send you to the psycho ward.
1961		T.I. Rubin In the Life 31: What the hell, I could have been psycho, maybe got shoved in the nut house.
1967		I. Rosenthal Sheeper 278: I [...] made him take me to the psycho ward.
1979		P. Hamill Deadly Piece 213: They [...] sent Ileana to a psycho ward.
1989		R. Atkinson Long Gray Line (1990) 327: Funny farm, loony bin, cuckoo’s nest, booby hatch, nut house, cracker box, psycho ward.
1999		N. Cohn Yes We have No 157: The next thing he knew, he was in the psycho ward.
2000		Guardian Rev. 15 Jan. 1: Rotting away in the adolescent psycho ward my father and step-mother had put me in.
2008		R. Price Lush Life 304: I’m a whack-a-doo! I’m a whack-a-doo! I got sent to the psycho doctor .

2. psychotic, violent, threatening.

1936		R. Chandler ‘Man who liked Dogs’ in Black Mask Mar. 19/1: Since when can a cop sign as complaining witness on a psycho case?
1942		R. Chandler High Window 149: He’s a psycho case, but we don’t want any psycho case made out of our pinch. We make that clear. We want a guy that don’t have any psycho record.
1953		E. Hemingway letter 26/25 Apr. in Baker Sel. Letters (1981) 820: He goes into almost psycho rages.
1963		J. Rechy City of Night 224: Someone who looks perfectly ‘normal’ and who turns out to be psycho — like the man [...] who had pulled a knife on me.
1975		J. Wambaugh Choirboys (1976) 230: I ain’t got nothing to do anyways except the progress report for our psycho captain.
1985		N. Pileggi Wiseguy (2001) 51: He calls us psycho kids.
1997		N. Barlay Curvy Lovebox 188: Bab an’ the psycho horde are closin’ in.
1998		(con. 1986) G. Pelecanos Sweet Forever 223: Better tell that miniature psycho boy of yours and cousin An-tony the news.
2000		N. Griffiths Grits 126: Thur’s Roger, wuth two uv is psycho mates.
2004		E. Weiner Drop Dead, My Lovely (2005) 45: Fuck, you’re psycho, Jack.
2009		P. Temple Truth 132: ‘Not lovable then. So some violent drug thing, you’d say that?’ ‘Any kind of shit you care to name. The boy’s psycho’.
2010		J. Ellroy Hilliker Curse 6: Psycho losers loot a train loaded with gold bullion.
2016		A. Wheatle Crongton Knights 52: Staring vacantly ahead in that psycho way of his.
2018		I. Welsh Dead Man’s Trousers 105: Purely in order to get that psycho cunt off my back.
2021		J. Ellroy Widespread Panic 165: ‘You’re not a Communist or a psycho killer, are you?’.

3. weird, eccentric, bizarre, mad.

1951		E. Hemingway in Baker Sel. Letters (1981) 11–12 Apr.: I know a lot of psycho stories too.
1963		J. Rechy City of Night 43: Stay away from him, spote, hes psycho.
1975		J. Wambaugh Choirboys (1976) 31: I think he’s got a leaky seabag. Dingaling. Psycho.
1988		H. Gould Double Bang 186: He did his psycho act and rolled over so he could look right up her skirt.
1998		Mack 10 ‘Ghetto Horror Show’ 🎵 I’m psycho like Norman Bates in the fresh side of my mind.
2004		C. Hiaasen Skinny Dip 213: I end up all alone with a psycho blackmailer.
2012		J. Fagan Panopticon (2013) 107: What if [...] I’ve gone psycho, just like my bio-mum? Clinical psychosis.
2021		J. Ellroy Widespread Panic 23: I busted a psycho kid blowtorching two lovebirds in a ’49 Ford.