Meaning

noun someone acting as an informer or decoy for the police

verb take by theft

verb give away information about somebody

originOrigin uncertain. Perhaps an alteration of Middle English snacche (“a trap, snare”), snacchen (“to seize (prey)”, whence modern English snatch). Compare also Middle English snik snak (“a sudden blow, snap”). Alternatively, perhaps from a dialectal variant of sneak, from Middle English sniken, from Old English snīcan (“to creep; crawl”). More at sneak.

Etymology from Wiktionary, CC BY-SA 3.0