Green’s Dictionary of Slang

1. LSD, i.e. d-lysergic acid diethylamide-25 [abbr. acid n.¹ (1)].

1971		E.E. Landy Underground Dict. (1972).
1977		L. Young et al. Recreational Drugs.
2001		ONDCP Street Terms 1: A — LSD.

2. amphetamine.

1967		R. Bronsteen Hippy’s Hbk.
1981		D.E. Miller Bk of Jargon 336: A: Amphetamines.
1990		(con. 1930s–60s) H. Huncke Guilty of Everything (1998) 289: A guy would come up with thirty or forty dollars to cop an ounce of A.
2002		J. Franzen Corrections 490: Inside were thirty golden pills. ‘My God.’ Denise laughed. ‘Mexican A.’.