Green’s Dictionary of Slang

1. a coat, a wrap [schmatte n.].

1900		Sporting Times 2 June 2/1: Their thoughts [...] mainly directed upon a ten-guinea ‘smother,’ which hangs suspended from one of the brow antlers of an Exmoor stag.
1935		Thieves Slang ms list from District Police Training Centre, Ryton-on-Dunsmore, Warwicks 10: Smother: Overcoat.
1937		J. Curtis You’re in the Racket, Too 111: What with this smother and an umbrella he looked just as good as anyone else.
1956		‘Charles Raven’ Und. Nights 21: She insisted on our leaving behind three of the finest pen-and-ink smothers I ever set eyes on.
1962		F. Norman Guntz 15: I was grafting again, and wearing a white smother.
1977		D. Powis Signs of Crime 201: Smother Overcoat (probably from Yiddish ‘schmutter’).
1989		(con. 1950s–60s) in G. Tremlett Little Legs 197: smother overcoat.
2003		Brummagem Dict. 🌐 smother n. a topcoat or overcoat.

2. (Aus.) a plan, an undercover stratagem; a subterfuge.

1902		Truth (Sydney) 3 Aug. 8/4: We could name several other ‘smothers’ where the proprietor combines the business of prostitution with that of criminal coddling [AND].
1903		Sporting News (Launceston) 23 May 2/6: He has a ‘smother’ which has saved him from many a well-directed blow, using this in preference to his feet [AND].
1986		R.G. Barrett Godson 22: ‘[H]e legs it rather than have his smother blown’.
1992		R.G. Barrett White Shoes 260: All the lairising and running around. It was just a big smother.

3. (Aus.) the surrounding of a victim who is to be robbed.

1915

Drew & Evans Grafter (1922) 4: ‘[Y]ou’ll have to get to work on that [betting] ticket [...] Get some of the boys to give you a smother, and when he goes to put it in, dive on it and see you don’t miss’.

4. (UK Und.) a place used to hide stolen goods.

1937

E. Raymond Marsh 28: Some of the houses were well known as ‘smothers,’ where burglars planted their swag.

5. (Aus. prison) the surrounding of a prisoner to obscure them from the guards during a prison break.

2006

B. Matthews Intractable [ebook] [They] gave me a smother while I climbed into a chaff bag and hid inside the box.