Green’s Dictionary of Slang

wet n.

1. with ref. to liquids.

(a) [late 17C+] (also whet) a (measure of) alcohol, often as take a w(h)et, to have a drink; thus wet stuff, alcohol.

(b) [late 19C–1930s] (US) an anti-Prohibitionist, who wants alcohol to remain legal.

(c) [1920s+] the act of urination.

(d) [1960s] (US campus) a drinking party.

2. [1930s+] (mainly UK juv., also wet end, wetso) an ineffectual, weak, foolish person.

3. see wetback n.

4. (US black / drugs) phencyclidine.

In compounds

wet money (n.)

money for the purchase of drink.

In phrases

light wet (n.)

[19C] gin.