Green’s Dictionary of Slang

1. one who snacks or eats between meals [nosh v. (1)].

1969		Sun. Times 23 Mar. 28: Hot meal vending machines in the lobby for late night noshers.
1999		Guardian Rev. 27 Nov. 6: He’s more of a nosher than a boozer.

2. a fellator/fellatrix [nosh v. (2)].

1978

H. Selby Jr Requiem for a Dream (1987) 10: Why do ya think the Jewish guys get all the broads? [...] It’s because we’re knoshers.