Green’s Dictionary of Slang

1. (Aus./US) a wild and unmanageable horse.

1885		Bulletin (Sydney) 7 Nov. 6/4: I [...] had gone away up North with a mob of stores, and was returning with a few horses, amongst them a very pretty half-bred mare, a real outlaw, though, not with wickedness so much as cunning, for she was as kind as a kitten until any of us attempted to sit her.
1899–1900		H. Lawson ‘The Buck-Jumper’ in Roderick (1972) 388: They reckon they’ve got the champion outlaw in the district — that chestnut horse in the yard.
1901		‘Rolf Boldrewood’ In Bad Company 176: The next animal was described as an ‘outlaw,’ a bush term for a horse which has been backed but never successfully ridden.
1912		Bulletin (Sydney) 12 Dec. 34/4: I was passin’ a selection in the bush, and was tellin’ ’em how I could ride an ’orse, and they put me up on an outlaw. I ’adn’t a hope.
1919		Van Loan ‘Chivalry in Carbon County’ in Score by Innings (2004) 320: Two carloads of broncs. Some of ’em outlaws.
1923–4		F. Anthony ‘Gus Buys a Horse’ in Me And Gus (1977) 19: He told us that the horse was a rank outlaw.
c.1940		‘The Castration of the Strawberry Roan’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 92: He’s the worst fuckin’ outlaw that ever been foaled, / He hadn’t been rode, and he’s twenty years old.
1957		J. Greenway ‘Aus. Cattle Lingo’ in AS XXXIII:3 167: outlaw, n. An unbreakable wild horse.
c.1968		‘Old Zebra Dun’ in G. Logsdon Whorehouse Bells Were Ringing (1995) 81: Old Dunny was an outlaw, but he didn’t let it show, / Till the stranger had him saddled and was ready for to go.

2. (US) a person who flouts conventional practices and regulations (whether in a respectable or criminal context).

1920		Harvey’s Weekly 19 June 11/1: No man who is a member of the union has a right to quit work unless the union bids him to quit. If he does he is an ‘outlaw’ [DA].
1949		in C. Hamilton Men of the Und. 179: I’ve even worked as an ‘outlaw’ — [...] used my own wrist watch as a prize, as flash, and operated whatever game I could on a couple of boxes.
1956		‘Toney Betts’ Across the Board 155: Among those O’Grady evicted were several punks, chiselers and tinhorns who tried to make book or tout without getting an okay. These are known to Pinkertons as ‘outlaws’.
1966		H.S. Thompson Hell’s Angels (1967) 14: We’re royalty among motorcycle outlaws, baby. [Ibid.] 273: There is an important difference between the words ‘loser’ and ‘outlaw’. One is passive and the other is active, and [...] the Angels are [...] acting out the day-dreams of millions of losers who don’t wear any defiant insignia and who don’t know how to be outlaws.

3. (US black) a prostitute without a regular pimp, or any independent prostitute.

1935		A.J. Pollock Und. Speaks.
1939		D. Maurer ‘Prostitutes and Criminal Argots’ in Lang. Und. (1981) 116/2: outlaw. A prostitute who does not give her earnings to her pimp.
1958		Murtagh & Harris Cast the First Stone 112: A girl without a man might’s well be without an arm or a leg [...] She’d be called an outlaw in the houses I used to work.
1965		K. Marlowe Mr Madam (1967) 146: ‘What’s an outlaw?’ ‘A single girl that hustles that ain’t got no pimp to hustle her.’.
1972		Milner & Milner Black Players 41: Insults or derogatory terms include bitch (this is entirely dependent on tone and context), tramp, and outlaw.