Green’s Dictionary of Slang

1. as a physical feature [supposed resemblance/based on colour].

2. a disagreeable, odd or irritable person.

1896		W.C. Gore Student Sl. in Cohen (1997) 12: prune n. One who is disagreeable and irritable.
1902		Ade Girl Proposition 139: He moved into a first-class, pruneless Family Hotel.
1915		M.G. Hayden ‘Terms Of Disparagement’ in DN IV:iii 200: That girl is certainly a prune. She’s fierce.
1919		Corpus Christi Caller (TX) 2 Nov. n.p.: [cartoon caption] I will not be beaten by that prune!
1926		Wood & Goddard Dict. Amer. Sl.
1960		J. Havoc Early Havoc 161: ‘You starched, dried-up prune’.
1977		(con. 1949) J.G. Dunne True Confessions (1979) 59: A Protestant prune, Dan T. Campion called Adela Perkins. Take a bite out of her and she’d flush you out like a physic.

3. a simpleton, a fool [note WWII RAF jargon P.O. (Pilot Officer) Prune, the personification of stupidity and incompetence. The character was created by Squadron Leader Anthony Armstrong and the artist ‘Raff’ (L.A.C. W. Hooper) to teach pupils and other flying personnel how things should not be done].

1900		E.H. Babbitt ‘College Words and Phrases’ in DN II:i 52: prune, n. A slow-witted fellow.
1915		S. Ford Shorty McCabe on the Job 189: Pyramid Gordon was white enough to want to divide his pile among the poor prunes he’d put out.
1918		J.N. Hall High Adventure 92: You poor, simple prune!
1924		H.L. Wilson Professor How Could You! 256: The prune says I am convinced beyond a shadow of a doubt that I have been deceived.
1931		P. Stevenson Gospel According to St Luke’s 24: He’d be a prune in School [...] always grinning—taking it from everybody. God! his brother a prune!
1938		Williamstown Chron. (Vic.) 12 Nov. 3/2: The customer was nicked twice with the razor and the ‘Prune’ was applying the astringent pencil.
1941		Baker Popular Dict. Aus. Sl. 57: Prune, a simpleton, fool.
1960		Wodehouse Jeeves in the Offing 166: What, if anything, does the young prune mean?
1972		B. Rodgers Queens’ Vernacular 61: a prick, a sap [...] prune.
1986		F. Taylor Auf Wiedersehen Pet Two 36: Ally’s fury at having to stand around the airport like a prune and then hail his own cab.
1999		Indep. Rev. 10 July 20: She would look a bit of a prune having lunch in a posh frock and fancy hat in Safeway’s car park.
2003		McGill Reed Dict. of N.Z. Sl. 152: pack of bludgers/deros/drongos/no-hopers/prunes, etc Unimpressive group, eg, ‘Look at those jokers all wearing floppy hats. What a pack of prunes!’.

4. (US campus) a mistake, a blunder.

1900

E.H. Babbitt ‘College Words and Phrases’ in DN II:i 52: prune, n. An error, mistake.

5. an unattractive, prudish woman.

1914		P.G. Wodehouse ‘Their Mutual Child’ in Munsey’s Mag. LI 900/2: Teel your Aunt Lora to make a noise like an ice-cream in the sun and melt away. She’s a prune, and what she sayas don’t go.
1965		F. Pollini Glover 304: Shoulduv jazzed her too. The old prune.
1984		Partridge DSUE (8th edn) 928/1: [...] later C.20.
1996		L. Pettiway Honey, Honey, Miss Thang 195: The ones I was dating they was older. I mean old. Seventy. [...] Who else would want a dried-up prune?

6. a person.

1923		Wodehouse Inimitable Jeeves 32: My heart warned to the poor prune.
1934		Wodehouse Right Ho, Jeeves 135: Frankly, I was shocked by the unfortunate young prune’s appearance.
1949		Wodehouse Mating Season 22: This young prune is one of those lissom girls of medium height.
1971		Wodehouse Much Obliged, Jeeves 55: A definitely nice young prune and just the sort to be a good wife.
1992		D. Jarman letter 12 Mar. Smiling in Slow Motion (2000) 93: Oscar at dinner with Gide in Paris, telling the old prune that his previous night’s lover had murdered his wife earlier in the week.
2000		Observer Rev. 19 Mar. 12: Susie’s husband, ‘old prune’ Angus, will convieniently keel over with a heart attack.
2023		R. Milward Man-Eating Typewriter 510: The prune at the desk probed us only a petty bit before handing over the clefs.