Synonyms:
fink, snitch, snitcher, stoolpigeon, stool_pigeon, stoolie, sneak, sneaker, canary
Meaning: someone acting as an informer or decoy for the police
Usage examples
"I must go over to Fink's," said the Kid, rising, "for some tobacco.
But there was a man named Fink who kept a store at the Crossing--a man of many nationalities, tongues, interests, and ways of thinking.