Green’s Dictionary of Slang

1. a remarkable or outstanding person or event [predates one n.¹ (5a) thus poss. Cockney pron. of SE wonder = wunner] .

1841		Dickens Old Curiosity Shop (1999) 432: Miss Sally’s such a one-er for that, she is.
1862		Thackeray Adventures of Philip (1899) 547: You should see her eat: she is such a oner at eating.
1873		J. Greenwood In Strange Company 7: I’d rather be without a mother than have a oner like her.
1887		Cumberland Mercury (NSW) 4 May 4/2: ‘[S]hip-shape and Bristol fashion’ means A1 [...] ‘A1’ is short for a one-er.
1891		T.B. Reed Cock House Fellsgarth 201: Wisdom used to say he could do it in three hours [...] But he was a wonner to go.
1893		P.H. Emerson Signor Lippo 34: I was always a one-er for the gab.
1894		Truth (Sydney) 6 May. 1/6: She is a wonner is the Missus.
1906		O.C. Malvery Soul Market 258: ‘He’s a one-er, ain’t he?’ said one of the women [...] in a tone of admiration.
1912		E. Pugh City Of The World 192: Little Johnny was a ‘wunner at his sums’.
1916		G. Jennings Poached Eggs and Pearls (1917) 15: george: That lady what’s waiting on us is a bit of all right, too. bill: Ah! she’s a one-er, she is.
1933		Goulburn Eve. Penny (NSW) 3 Jan. 1/6: They were a fast lot out there in Bueneos Ayres [...] she got into a tight corner, and her cousin, Mick Kennedy, he was a oner, if ever there was one.
1940		M. Marples Public School Slang 6: Words of general approval [...] wunner, otherwise one-er (1840, Dickens) [...] made familiar to many through the refrain of a music-hall song, ‘By gad ! he’s a wunner, a ripper, a stunner’.

2. (also onener) a knockout blow [one n.¹ (1)].

1845		J. Lindridge Sixteen-String Jack 84: There’s a one’r to set you going!
1860		Hotten Dict. of Modern Sl. etc. (2nd edn) 184: ONE-ER, that which stands for one, a blow that requires no more.
1861		cited in Partridge DSUE (1984) 830/2: 1861 Duncan Cook onener.
1867		‘Under the Earth’ in Dick’s Standard Plays (1871) II iii: I’ll fight him – hic – or any other man – hic – only a one-er in the ribs.
1874		J. Greenwood Wilds of London (1881) 9: On being threatened with a ‘oner in the mouth’ [...] she prudently had no more to say.
1881		Bulletin (Sydney) 28 May 4/2: Before the injured matron could / Recover from this stunner.,/ Behold Theresa had stepped back, / And landed her a ‘one-er’.
1884		Ally Sloper’s Half Holiday 10 May14/3: ‘Give the drum a one-er’.
1888		Aus. Star (Sydney) 22 Dec. 4/6: He would like to know [...] whether bricks or crowbars are generally used in these ‘physical demonstrations’ and further whether ‘suppression’ takes the form of a ‘oner on the wind’.
1890		Dead Bird (Sydney) 31 May 1/3: She had snatched off her fairy boot and given him one of the best double-breasted oners that had ever been heard of.
1909		J. Ware Passing Eng. of the Victorian Era 188/2: Oner over the gash (Peoples’). A blow over the mouth.
1934		Chron. (Adelaide) 25 Jan. 63/5: That new chum was quick; he let drive a oner before Snapper had has guard up— sort of a right upper cut which nearly shot Snapper’s eyes into his skull.
1945		(con. 1928) R. Westerby Mad in Pursuit 103: Coo, didn’t half gimme a oner last round.

3. of a woman, one who appears to exceed ‘respectable’ standards of dress and behaviour.

1889

Sheffield Wkly Teleg. 16 Nov. 2/2: ‘You saw me with a woman last night [...] “a regular oner, painted cheeks and yellow hair.” I heard your description of her appearance and of her digusting conditon. That woman is my wife’.

4. in monetary uses.

5. (Aus.) a ‘character’, an amusing or eccentric person, or joke.

1917		Nat. Advocate (Bathurst, NSW) 13 Sept. 4/4: Dick gave a howl of delight. [...] ‘Good old Jecks! You’re a oner, and no mistake!’.
1959		Baker Drum 131: Oner, an amusing or eccentric person.
1986		Chapman NDAS 304/2: That was a great joke, a oner.

6. a single swallow.

2012		(con. 1980s) I. Welsh Skagboys 7: Dad knocks his [whisky] back in a oner.
2018		I. Welsh Dead Man’s Trousers [15]: His hand fastens around the glass of vodka and tonic. He downs it in a oner.

7. immediately.

2013

T. Black Ringer [ebook] n.p.: The car starts in a oner.