fink

(noun) someone acting as an informer or decoy for the police. Synonyms: snitch, snitcher, stoolpigeon, stool pigeon, stoolie, sneak, sneaker, canary.

(verb) take the place of work of someone on strike. Synonyms: scab, rat, blackleg.

(verb) confess to a punishable or reprehensible deed, usually under pressure. Synonyms: confess, squeal.