Green’s Dictionary of Slang

1. cocaine.

2001

ONDCP Street Terms 18: Roxanne — Cocaine; crack.

2. freebase, later crack cocaine.

2001		ONDCP Street Terms 18: Roxanne — Cocaine; crack [...] Rox — Crack Cocaine.
2003		(ref. to 1981) J. Lethem Fortress of Solitude 251: It’s 1981: nobody’s heard the term crack [...] What’s slipped lately onto the street [...] is called variously base-rock, gravel, baking-soda-base and roxanne.