Green’s Dictionary of Slang

slug v.2

[slug n.2 (1)]

1. [mid-19C+] to hit hard; often ext. as slug it out.

2. [late 19C] to criticize harshly.

3. [late 19C–1900s] in fig. use, to overcome.

4. [late 19C+] (also slug around) in fig. use, to dispute aggressively; often ext. as slug it out.

5. in fig. use of sense 1 .

6. [1910s–40s] to shoot.

7. [1920s+] (US) to trudge, to move with an effort, to make an effort; thus slugging adj.

8. [1930s] to kill, to murder.

9. [1940s+] (Aus.) to overcharge.

10. [1960s] (US) to apply, to dose.

In derivatives

slugfest (n.) [-fest sfx]

[1910s+] (US) a rough battle, a hard-hitting contest.

sluggy (adj.)

[1950s] (US teen) violent, aggressive.