Meaning

noun someone acting as an informer or decoy for the police

verb take the place of work of someone on strike

verb confess to a punishable or reprehensible deed, usually under pressure

originUnknown; first attested in 1894. A connection to Yiddish as some propose is unlikely. Suggested origins include: * German Fink (“finch; frivolous or dissolute person; informer”) as finches are notoriously chatty birds in groups. If so, then Doublet of finch. Compare canary (“informer”). * Partly from the German theory, a fanciful association by students with the freedom of wild birds as opposed…

Etymology from Wiktionary, CC BY-SA 3.0