Green’s Dictionary of Slang

1. an ex-husband, ex-wife, ex-lover, the other half of a lapsed relationship.

[1827		T. Moore Cash, Corn and Catholics 125: But don’t you perceive, dear, the Church have found out That you’re one of the people call’d Ex’s [i.e. an ‘ex-Catholic’] at present?].
1921		Broadway Brevities Dec 20: Is it true that Bee Savage is to hit the matrimonial hurdles with Larry Sabellos? Wonder if she'll have better luck than Mona, the ex?
1929		E. Wilson I Thought of Daisy 96: ‘Phil was your first husband, was he?’ ‘Yes: he’s my ex,’ she said.
1939		W. Winchell On Broadway 29 Sept. [synd. col.] [He] declared he was going to work as a butler – for her ex.
1941		‘Digg Mee’ ‘Observation Post’ in N.Y. Age 15 Mar. 9/6: From what I hear, two ‘exes’ were very near and from their spiel in may be real.
1954		B. Appel Sweet Money Girl 51: I just had to get a break sometime. A break to make up for my ex, Ronny.
1963		G. Marx letter 11 Apr. in Groucho Letters (1967) 53: That’s Howard Hawk’s ex.
1977		C. McFadden Serial 32: What had happened to her ex.
1989		C. Hiaasen Skin Tight 272: There’s your ex, and Murdock and Salazar – another funeral.
2003		N. Green Angel of Montague Street (2004) 239: Stiff my ex out of her alimony.
2005		P. Temple Broken Shore (2007) [ebook] My ex went to Darwin [...] couldn’t hack it.
2005		H. Mantel Beyond Black 326: You ask my ex.
2010		(con. 1973) C. Stella Johnny Porno 21: Your other ex might be able to help me out there.
2010		L. Redhead Thrill City [ebook] Statistically, women are most likely to be murdered by their exes.
2012		R. Milward Kimberly’s Capital Punishment (2023) 215: I could hear my weekly exes mumbling and grumbling.
2017		V. McDermid Insidious Intent (2018) 108: ‘Kathryn may have had a run-in with her ex’.
2021		J. Ellroy Widespread Panic 133: Joi Lansing was my ex.
2021		Central Cee ‘Committment Issues’ 🎵 I know that your ex still miss you.
2021		L. McInerney Rules of Revelation 111: Her straight friends had exes: boys they had outgrown, men who had outgrown them, or guys revealed to be bastards or cowards.

2. (US prison) an ex-convict.

1906		E. Hubbard Love, Life and Work 🌐 The Ex. now is a totally different man from the Ex. just out of his striped suit in the seventies.
1908		J. Kelley Thirteen Years in Oregon Penitentiary 56: The people who make the most talk about an ‘ex.’ nine times out of ten if they had what was coming to them they would be behind bars.
1912		Labor World (Duluth, MN) 19 Oct. 5/1: Well, send the ‘ex’ to me [...] That ‘con’ can’t live it down.
1926		‘Und. and Its Vernacular’ in Clues mag. 158—62: X, ex Ex-convict.
1938		cited in Partridge DU (1949) 223/2: ‘since ca. 1925’.
1962		Ragen & Finston World’s Toughest Prison 789: AN ‘X’–An ex-convict.
1971		(con. 1960s) J. Brown Monkey Off My Back (1972) 143: A gathering of hundreds of convicts who were taking their free-time [...] to get together and listen to an ‘ex’.