Green’s Dictionary of Slang

Cadillac n.

[the perceived characteristic of the expensive marque]

1. (US) in drug uses.

(a) [1930s+] a 28g (1oz) packet of a powdered drug.

(b) [1950s+] any powdered, thus usu. narcotic, drug.

(c) [1970s+] phencyclidine.

2. [1990s+] (US) in prison uses.

(a) coffee with cream and sugar.

(b) (also car) a line used for transferring articles, e.g. a pack of cigarettes, from one cell to another.

(c) an easy job within the prison.

(d) (also Cadillacker) something considered the best.

(e) a vacant cell.

SE in slang uses

In compounds

Cadillac commie (n.) [the Cadillac is trad. antipathetic to left-wing ideology]

[1990s+] (US) a liberal, the intensity of whose pronouncements on social problems is in direct proportion to their ability to escape their existence.