Plural of narc; undercover police officers or agents who investigate illegal drug use and sales, or informal slang for informants.
Short form of 'narcotics' officer, from Greek 'narke' meaning numbness or stupor. The word gained popularity in the 1960s as slang for drug enforcement agents.
The term 'narc' became so associated with undercover drug cops in American culture that it spawned entire genres of crime fiction—but interestingly, real narcotics officers rarely use the term themselves because it's considered dated slang.
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