Green’s Dictionary of Slang

1. a person.

1924		Townsville Daily Bulletin (Qld) 22 Nov. 4s/3: We heard the gun blazing away [...] and we reckoned chummy was doing well with the birds.
1944		C. Fluck ‘Bubbles’ of the Old Kent Road 26: I’m off to Bo Peep and in the morning I’ll make Chummy a cup of Rosy Lee.
1955		B. Hill Boss of Britain’s Underworld 100: Chummy could not handle such a large amount [i.e. of stolen ration coupons] and offered them to me.
1970		R. Fabian Anatomy of Crime 39: Chummy is expert at sneaking in even when a home is occupied.
1983		A. Payne ‘Senior Citizen Caine’ Minder [TV script] 10: Hang on, is that chummy over there?
1989		J. Morton Lowspeak 39: Chummy – anyone of whom a policeman is speaking but usually a suspect.
1997		H.R.F. Keating Soft Detective 15: Looks as if chummy went out by the french windows.
2004		B. Parris Making of a Legionnaire 37: The French kid was a real bully [...] I would have to keep an eye on chummy from now on .

2. see chum n.

3. see new chum n. (1)