rat

[1]	fink , scab , blackleg
[2]	denounce , tell on , betray , give away , grass , shit , shop , snitch , stag

[1]	scab , strikebreaker , blackleg
[2]	rotter , dirty dog , skunk , stinker , stinkpot , bum , puke , crumb , lowlife , scum bag , so-and-so , git
[3]	informer , betrayer , squealer , blabber