Green’s Dictionary of Slang

1. (UK Und.) anyone, usu. an inn-keeper, who provides and stables horses for a highwayman.

1608		Dekker The Belman of London H4: In this Colts house will they sit carowsing [...] drawing the Host and Hostesse on to beleeue they shall be made for euer by these guests the better, [...] draw all their acquaintance they can to the house.
c.1698		B.E. Dict. Canting Crew n.p.: Colt c. an Inn-keeper that lends a Horse to a Highway-man, or to Gentlemen Beggers.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict.
1848		Flash Dict. in Sinks of London Laid Open.
c.1850		Duncombe New and Improved Flash Dict.
1859		Matsell Vocabulum 20: coltman. One who lets horses and vehicles to burglars.
1895		Crowe Aus. Sl. Dict. 19: Coltman, a burglar’s livery-stable keeper.

2. a young man who has just been initiated into crime.

1627		J. Taylor ‘An Armado’ in Works (1869) I 91: Traps for vermin, Grinnes for wild Guls, Baytes for tame Fooles, Sprindges for Woodcockes, Pursenets for Connies, Toyles for mad Buckes, Pennes for Geese, Hookes for Gudgeons, Snares for Buzzards, Bridles for old Iades, Curbes for Colts, Pitfals for Bulfinches and Hempen-slips for Asses.
1658		R. Brathwait Honest Ghost 89: A roaring Haxter, Pandor, Palliard, Bolt, Pimp, Snap, Shark, Cheat, or any such like Colt.
1725		New Canting Dict.
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. 1725].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.

3. a new apprentice, modern use is usu. in sporting context.

c.1698		B.E. Dict. Canting Crew n.p.: Colt [...] a Lad newly bound Prentice.
1885		Daily News 28 Aug. 3, col. 7: A match arranged for the benefit of the young players [...] when the Lancashire Eleven were opposed to Twenty-six colts [F&H].
1895		Crowe Aus. Sl. Dict. 19: Colt, [...] a professional cricketer doing his first season.

4. a young girl sold into prostitution.

1667		Dryden Sir Martin Mar-all IV i: I like a Colt that never yet was back’d.
1788		G.A. Stevens Adventures of a Speculist I 249: She is called a Colt; the Pimp has a pound or two for his trouble; and the girl, thus bought, is obliged to do just as her purchaser pleases.

5. one who serves on a jury for the first time.

1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1864, 1867, 1870		Hotten Sl. Dict.
1895		Crowe Aus. Sl. Dict. 19: Colt, a person who sits as a juryman for the first time.
1935		A.J. Pollock Und. Speaks 24/2: Colts, the jury.

6. a neophyte prostitute, recently picked up in the country and ‘recruited’ by a bawd who scouts for such girls in their early teens.

c.1850

Peeping Tom (London) 10 38/1: The unconscious creatures [...] are stipped, washed and finely clothed. The victim is called a ‘colt’.

7. a (young) man.

1903		Bulletin (Sydney) 24 Dec. 36/1: Live while ye’er young – give the colt ’is ’ead: / Life’s time is short – we’ll be a long time dead.
1944		D. Burley Orig. Hbk of Harlem Jive 65: I don’t dig no colts.
1958		Murtagh & Harris Cast the First Stone 23: A lush, ripe sixteen with a figure that the colts at Monkey’s called a ‘coke frame – streamlined like a Coca-Cola bottle.’.