Green’s Dictionary of Slang

kiss off v.

[? billiards use or the offering of a farewell kiss]

1. [20C+] to sidetrack someone or something, to marginalize, to slight or disregard.

2. [1910s+] (US) to murder or to die.

3. [1930s] to defraud, to cheat.

4. [1930s+] to reject, to ignore, to spurn, esp. a lover; thus excl. kiss off!, go away, don’t talk rubbish!

5. [1930s+] (also kiss out) to bring to an end.

6. [1950s] to come to an end.

7. [1950s-60s] (US) to leave; leave alone; also as excl. go away!