1. [1930s] (US Und.) to knock out or down.
2. [1930s–40s] (US Und.) to stack a deck of cards prior to using them in a cheating card-game.
3. [1930s+] to murder, to assassinate.
4. [1930s+] to give up on, to abandon, to ignore.
5. [1930s+] (US Und.) to deal with, to nullify, e.g. a criminal charge.
6. [1940s] (US Und.) for the victim of a confidence trick to lose interest.
7. [1940s+] (orig. US) to become emotionally cold, withdrawn.
8. [1940s+] (US) to tolerate, to make no fuss about.
9. see chill (out) v.
[1900s–50s] (US) to (pretend to) ignore.
see separate entry.
[1980s] (US black) to undermine someone’s plans.