Green’s Dictionary of Slang

(drugs) marijuana, a marijuana cigarette.

1949		Monteleone Criminal Sl. (rev. edn).
1952		Lannoy & Masterson ‘Teen-age Hophead Jargon’ AS XXVII:1 28: MARI, n. Marijuana [LAPD].
2001		ONDCP Street Terms 14: Mari — Marijuana cigarette.