1. [late 17C; mid-19C+] in hetero- or homosexual senses, sexual activity, spec. sexual intercourse.
2. [1930s+] in a physical sense, movement indicative of sexuality, i.e. the erotic ‘action’ of the hips or pelvis.
3. [late 19C+] (US) financial transactions, esp. bets and wagers.
4. [20C+] (orig. US black) what is going on; thus a situation or state of affairs, anything exciting, current, interesting, depending on the context, e.g. the chance for sex, a musical performance, a night’s gambling; often used in the greeting, Where’s/what’s the action?
5. [1950s–60s] the potential client for a prostitute, or victim of a confidence trick etc.
6. [1950s–60s] (US) one’s choice, one’s preference.
7. [1960s] the effects of a drug.
8. [1960s] (US) a revolver.
9. [1960s–70s] manipulations, activities, esp. when illegal or corrupt.
10. [1960s–70s] (drugs) the current availability of drugs and opportunity to obtain them.
11. [1960s+] (orig. US black) a woman.
12. [1970s+] (orig. US black) a response or acknowledgement, whether verbal or physical, esp. when flirtatious.
13. [1990s+] (Aus. prison) homosexuality.
1. [1980s] a woman [piece n. (1a)].
2. [2000s] a gun [piece n. (3a)].
[1940s–70s] (US black, mainly Harlem) ready for anything.