Green’s Dictionary of Slang

1. a mistress, a prostitute [ironic use of SE].

1688		implied in purest pure below.
1691		Mundus Foppensis 13: Go but three yards from the street, And you with a new Language meet: [...] Pure, Tackle, Buttock, Purest pure.
c.1698		B.E. Dict. Canting Crew n.p.: Pure c. a Mistress.
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.
1811		Lex. Balatronicum.
1835		Comic Almanack Dec. 38: Now let not those who’ve ’scaped my blows believe that I am fickle, / For many a ‘Pure’ who looks demure, I’ve put a rod in pickle, And if I’m here another year their backs I’ll smartly tickle.
1997–2000		Da Bomb 🌐 23: Pure: A kept woman; a mistress.

2. top quality, unadulterated drugs.

1915		G. Bronson-Howard God’s Man 249: ‘I’ve got two hundred cans to sell – the pure stuff.’ [...] The government might have wind of the syndicate’s operations and have sent this man to offer him the interdicted smoking-opium.
1959		Murtagh & Harris Who Live In Shadow (1960) 104: I will give you two kilos of pure.
1974		R. Stone Dog Soldiers (1976) 13: That’ll learn you, messing with pure. Don’t get sick on my cushion.
1978		H. Selby Jr Requiem for a Dream (1987) 9: We’d get a pound of pure and just sit back and count the bread.
1989		(con. 1982–6) T. Williams Cocaine Kids (1990) 115: He always wanted me to bring pure, no flake, just rocks.
2006		F.X. Toole Pound for Pound 197: Then who you go to for your drugstore pure?

3. (drugs) the best heroin.

1969		‘Iceberg Slim’ Pimp 75: Old ‘Weeping’ fell dead outside a shooting gallery. [...] Musta shot some ‘pure’.
1974		V.E. Smith Jones Men 88: I’ll let you have two pounds to start. New York Pure, no more than one cut.
1993		Smith & Noble Neddy (1998) 247: Murray said that the guy had heard of me and wanted to meet me before he would discuss selling the gear. [...] I went to see him – and work out a plan to relieve him of six kilos of pure. [...] He agreed to give me the heroin for $100,000 per pound if I bought in bulk.
2001		ONDCP Street Terms 17: Pure — Heroin.