Green’s Dictionary of Slang

(orig. US drugs) mescaline.

1969		R.R. Lingeman Drugs from A to Z (1970).
1971		Harper’s Mag. Sept. 63: [He] is off everything at the moment — pot, hash, speed, acid, STP, mesc, psyl, coke, scag — because ‘It’s all a bummer, man; I got my head together’.
1981		S. King Roadwork in Bachman Books (1995) 476: ‘You’re probably peaking now. Is it very visual mesc?’ ‘Yes. A little too visual.’.
1996		Eble Sl. and Sociability 36: The most frequent pattern of clipping is the loss of sounds from the ends of words: [...] mesc, from mescaline.
2001		ONDCP Street Terms 15: Mesc [...] Mezc — Mescaline.