Green’s Dictionary of Slang

reefer n.1

also reef
[abbr. greefo n.]
[1920s+] (drugs)

1. a marijuana cigarette, esp. a large and slender version.

2. marijuana.

3. attrib. use of sense 2.

4. someone who smokes marijuana.

In derivatives

reefered (adj.)

[1980s] (US drugs) intoxicated by marijuana.

In compounds

reefer-head (n.) [-head sfx (4)]

[1930s] (US drugs) a smoker of marijuana.

reefer man (n.)

1. [1920s-30s] (US drugs) a smoker of cannabis.

2. [1920s+] (drugs) a marijuana seller.

reefer pad (n.) (also reefer den, reefer flat, reefer joint) [joint n. (3b)/pad n.2 (2)]

[1930s–60s] (drugs) a house, apartment or room where cannabis users can gather to smoke.

reefer rat (n.)

[1930–50s] (US black/drugs) a marijuana smoker.

reefing man (n.)

[1930s–50s] (US drugs) a marijuana smoker.

In phrases

bang a reefer (v.)

[1950s] to smoke marijuana.