Green’s Dictionary of Slang

1. a partnership, esp. a group of musicians.

1935		Metronome May 28: As a soft fiddle-sax combo, it clicks.
1942		‘Marienne’ ‘Solid Meddlin’’ in People’s Voice (NY) 21 Mar. 33/1: Ella Fitzgerald will soon become part of the Ink Spots — what a combo!!!
1949		Music Library Association Notes Dec. 41: Combo: abbrev. of ‘combination.’ Refers generally to an instrumental group usually smaller than a band.
1953		L. Durst Jives of Dr. Hepcat (1989) 5: Just as soon as the canary pulls her number, the combo breaks out like the measles and presses much ether.
1959		Mad mag. Sept. 41: A hot combo of the hipsters, by the hipsters and for the hipsters shall not cut out.
1966		T. Keyes All Night Stand 94: These Yank airforce combos they have, they get me to sit in.
1972		D. Jenkins Semi-Tough 220: Those who didn’t mind leaving other parts of the lawn where the rock combos were playing.
1982		Time Out 10–16 Dec. n.p.: His self-styled punk rock combo [KH].
1992		R.G. Barrett White Shoes 110: A two-piece combo warbling some old Hall and Oates song.
1999		N. Cohn Yes We have No 297: A combo is playing swing on the bandstand.
2000		Observer Screen 16 Jan. 24: I rented a top-floor flat from an elderly brother-and-sister combo.
2016		T. Robinson Rough Trade [ebook] ‘His [jazz] combo booked some dates in Europe’.

2. (UK/US Und.) a combination lock (on a safe).

1931		AS ‘Und. Argot’ Dec. 107: combo: combination of a safe.
1948		J.M. Cain Moth (1950) 174: My fingers kept working the combo.
1959		E. De Roo Young Wolves 71: You got my combo out of Chief’s office, didn’t ya?
2015		S. King Finders Keepers (2016) 7: ‘Now the combo,’ said Mr Blue. ‘He snapped his gloved fingers. Give it up’.

3. (US) any form of combination, whether of people, things, sandwich ingredients, wagers etc.

1933		Ersine Und. and Prison Sl. 28: combo, n. The ingredients of a meal, ready for cooking; a meal.
1946		De Vries & Bushkin ‘Boogie Woogie Blue Plate’ 🎵 You can hear her calling orders like this [...] ‘Give me a triple beef on a load of hay / Combo rye and a bottle of aye’.
1952		(con. 1920s) ‘Harry Grey’ Hoods (1953) 265: ‘The Combo taking the union over?’ Lefty asked.
1959		E. De Roo Young Wolves 106: I got a winning combo and I want to keep it that way.
1962		L. M. Ackerman ‘Miscellany’ in AS XXXVII:1 79: A food combination may now be called a combo, as in the following examples: ‘Potluck Supper on Slate? Take chicken-rice combo’.
1967		Letter in Edelman Dear America (1985) 8 Feb. 153: That cozy spot known as the ‘Pink Pussycat,’ a combo bachelor officer quarters and social club.
1973		A. Bennett Habeus Corpus Act I: I think they’ve clicked, Scorpio and Sagittarius. Lovely combo.
1981		J. Ellroy Brown’s Requiem 150: To the right of the living room was a kiddie-room-sewing-room combo.
1992		J. Mowry Way Past Cool 100: The combo of beer and the cops on top of confronting the gang of young boys had stretched even his patience thin.
1999		Observer Mag. 25 July 23: With the pills, it was an unbelievable combo. Plus the crazy men.
2002		J. Ridley Conversation with the Mann 89: Men and men were routine, same with women and women, and men and men who dressed like women, and any other combo you could dream up.
2011		J.J. Connolly Viva La Madness 290: Morty is driving and he’s livid, not a good combo.
2011		C. Rhatigan ‘October 17 ... Meeting’ in Pulp Ink [ebook] I need fire running through my veins for this. Instead I’ve got a combo of caffeine, nicotine and dexedrine.
2017		T. Pluck Bad Boy Boogie [ebook] [of punches] Jay took a combo that sent him to his knees.
2021		S.A. Crosby Razorblade Tears 77: [of punches] He followed that up with a one-two combo to the ribs.

4. a relationship.

1959

C. MacInnes Absolute Beginners 60: You ever had that combo [i.e. a loving relationship].

5. (US campus) a bisexual person.

1989

(con. 1960s) M. Kingston Tripmaster Monkey 78: Pseudo psycho lesbo sappho weirdo hetero homo combos.