witch, the, n. — Green’s Dictionary of Slang

witch, the n.

[? it ‘bewitches’ the user]

(drugs) heroin, cocaine, morphine.

1949		Monteleone Criminal Sl. (rev. edn).
1953		Anslinger & Tompkins Traffic In Narcotics 316: witch. Cocaine, morphine, or heroin.
1977		S.N. Pradhan Drug Abuse.
2001		ONDCP Street Terms 22: Witch — Cocaine; heroin.