Green’s Dictionary of Slang

1. a professional fighter (and as such used as a professional nickname).

1888		J. Greenwood Policeman’s Lantern 35: [title] The Man-Basher. [Ibid.] 44: ‘Does that mean for simply knocking him down?’ [...] ‘It means whatever you mean,’ returned the professional ‘basher’.
c.1923		G. Robey [perf.] ‘All for the Best’ 🎵 Joe Bonzo the Birmingham Basher.
1927		Daily Tel. 11 Oct. 12/6: He fights as if he enjoys fighting; and there is much of a basher in him [OED].
1935		C. Drew ‘Ginger’ in Bulletin 24 July 50/1: The biggest of the heavies called himself Basher Kelly, and looked the part.
1937		Portsmouth Eve. News 15 May 10/6: A Special Arranged Heavyweight Match [...] Geo. Finnie v. Charlie Basher Green (the Wigan Thunderbolt).

2. a thug; also attrib.

1882		Theatre VI 40: A ‘man-basher’ [...] is an individual who, for a certain sum of money, will get any obnoxious person of your acquaintance out of the way, and secure his ultimate discovery in the River Thames.
1899		C. Rook Hooligan Nights 15: The basher of toffs flourishes in the Kingsland Road.
1915		T. Burke Nights in Town 299: A Basher’s Night Out.
1926		Yorks. Eve. Post 4 Oct. 7/2: The Connemara Basher [...] picked up a brick, which he threw the window. He said, ‘I will fight the six best men in Huddersfield. I come from Connemara where I mopped the whole town up’.
1929		Brisbane Courier 30 Sept. 12/6: ‘Basher’ gangs [...] have been wandering around Sydney for months intimidating men who were honestly working.
1936		D. Stivens Tramp and Other Stories 25: Making us into a basher-gang!
1944		Gloucs. Echo 4 Nov. 1/5: The father of ‘Basher’ Bates, the dead Normandy V.C., will not sell his son’s clothes.
1948		Smith’s Wkly (Sydney) 25 Dec. 6/3: May-I [...] wanted for him to become a prominent business man, like a high-class basher.
1951		Cusack & James Come in Spinner (1960) 203: This place is lousy with bashers and thugs.
1959		J. Gosling Ghost Squad 98: Basher Field, a real villain [...] a tough, wizened old fellow whose punishments had included the ‘cat’ .
1965		W. Dick Bunch of Ratbags 172: Most of the participants were small-time crooks, standover men, S.P. bookies, perverts, bashers and street-fighters.
1973		(con. 1930s) F. Huelin ‘Keep Moving’ 49: These railway basher gangs operated as legal extensions of the police force [...] They were physically big and mentally small, and all considered themselves much superior to their victims.
1973		(con. 1940s–60s) Hogbotel & ffuckes ‘The Bastard from the Bush’ in Snatches and Lays 82: Let’s make him our star basher, he’ll live up to his name.
1996		(con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 153: Those gangs of Pommy bashers he’d heard so much about.
2000		J.J. Connolly Layer Cake 8: Down in the lower levels of this swindle you need your bashers, people respond.
2004		T. Winton ‘Cockleshell’ in Turning (2005) 123: In his day he was a professional rabble-rouser, a drunk, a basher.
2011		J.J. Connolly Viva La Madness 103: Sonny’s a basher but he’s grafted, through hard work and ruthlessness.

3. (Aus.) a pimp.

1901

Sydney Sportsman (Surry Hills, NSW) 27 Feb. 6/6: ‘Don't you go & tell yer basher’— / He continues very mild; / At witch she becomes indignent. / Like a silly little child.

4. (UK Und.) that member of a smash-and-grab team who breaks the shop window.

1941

V. Davis Phenomena in Crime 136: The ‘basher’ breaks the windows or grilles.

5. a prostitute.

1963–74

B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 79: He could write a book that’d bring a blush to the cheeks of Betty the Bondi Beach basher.

6. (Aus. prison) a notably violent prison officer.

1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Basher. A prison officer renowned for using the baton. Term is often associated with pre-Nagle Bathurst Gaol (NSW), as in ‘the Bathurst Bashers’.
2006		B. Matthews Intractable [ebook] He was one of the old bashers who [...] became notorious for brandishing a loaded shotgun at prisoners during the 1970 Bathurst strike.