Green’s Dictionary of Slang

derail n.

1. [1920s–30s] (US campus) an unpopular student [HDAS, citing Weseen, Dict. of American Sl. (1934), suggests that this may be a mis-reading, but it may equally be be a separate or fig./ext. use of sense 2].

2. [1920s–50s] (US/N.Z.) denatured or adulterated alcohol, as drunk by alcoholics, tramps etc.

3. [1930s] a person who becomes ill through drinking such liquor.