kiss off v.
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!