oncer, n. — Green’s Dictionary of Slang

oncer n.

1. of a single action.

(a) a person who only goes to church once on Sunday; thus twicer, one who goes to both matins and evensong.

1919

World (Hobart) 25 Feb. 4/4: Last Sunday a well-known Hobart clergyman rather startled his congregation by announcing that he had a strong predilection for ‘twicers.’ [...] what the preacher so much desired was parishioners who went twice to worship on Sunday, and not once. The ‘oncers’ looked guiltily at each other, and the ‘twicers’ were conspicuous by their absence.

(b) (Aus.) anything that happens only once.

1968		G. Slatter Pagan Game (1969) 131: This game is vital to us because it’s a oncer game.
1970		H.E. Bates A Little of What You Fancy (1985) 495: I’m what we call in Australia a ‘oncer’. I went once and never again.

1932

‘R. Scully’ Scarlet Pansy 145: Fay Etrange had become a oncer – that is, she was through with one man after one experience.

(d) (gay) a homosexual who never repeats a sexual encounter with any one partner but continues to seek new people; thus oncing, refusing a second sexual act.

1941		G. Legman ‘Lang. of Homosexuality’ Appendix VII in Henry Sex Variants.
1949		‘Swasarnt Nerf’ et al. Gay Girl’s Guide 13: oncer: Passé term for homosexual addicted to ‘one-night-stands.’.
1962		J. Ellis Gay Girl [ebook] This wasn’t a girl like the regular trade here [...] not cheap, promiscuous, someone to throw into bed for a night and then forget. This wasn’t a ‘oncer’.
1965		Guild Dict. Homosexual Terms 33: oncer (n.): The homosexual who will have but one sexual experience with a person. (v.): oncing. The act of refusing a second sexual act.
1972		B. Rodgers Queens’ Vernacular.

(e) (US) a man who can only have one orgasm during one session of sexual activity.

1966

Trimble 5000 Adult Sex Words and Phrases 142: oncer (Sl.) a male capable of only one Orgasm during a Sex session.

2. a £1 note; a A$1 bill.

1931		Sunderland Dly Echo 2 Oct. 12/4: ‘Oncer’ [...] a sovereign.
1938		J. Curtis They Drive by Night 57: Once she had got off with a bloke there and he and his pal had taken her for a ride in a private car and each of them had dropped her a oncer.
1946		S. Jackson Indiscreet Guide to Soho 121: Do odd jobs of any kind for a couple of drinks and a ‘oncer’ (a pound note).
1953		K. Tennant Joyful Condemned 27: Sure he took your oncer. But look [...] here’s another quid in place of it.
1955		B. Hill Boss of Britain’s Underworld 31: I never left my flat without a century in oncers on me.
1967		‘Whisper All Aussie Dict.’ in Kings Cross Whisper (Sydney) xxxviii 10/1: oncer: One pound. One dollar.
1971		N. Smith Gumshoe (1998) 74: He sat behind his desk counting the take — fivers, oncers, ten bob pieces and shillings everywhere.
1989		in G. Tremlett Little Legs 196: oncer £1.
1998		R. Rendell A Sight for Sore Eyes (1999) 157: There were still pound notes in those days. Oncers.

3. a spree.

1941

Aberdeen Jrnl 7 Mar. 2/4: I heard of people drinking a ‘black velvet’ [...] to cheer themselves up, of war workers having a ‘oncer’ (a good time) when they can.

4. (Aus. prison) a single, experimental homosexual experience.

1984

B. Ellem Doing Time 129: Other guys may have a homosexual experience, a oncer, just to try it out.