[1] : WordNet (r) 2.0

narc
     n : a lawman concerned with narcotics violations syn: nark, narcotics
         agent
see also:
nark narcotics agent 

[2] : Moby Thesaurus II by Grady Ward, 1.0

103 moby thesaurus words for "narc":
   bow street runner, fbi, fbi agent, federal, g-man, mp,
   secret service, sherlock holmes, t-man, bailiff, beadle, beagle,
   bear witness against, betray, betrayer, blab, blabber, blabberer,
   blabbermouth, blow the whistle, bound bailiff, captain, catchpole,
   chief of police, commissioner, constable, delator, deputy,
   deputy sheriff, detective, fed, federal, fink, flic, gendarme,
   government man, hotel detective, house detective, house dick,
   inform against, inform on, informer, inquiry agent, inspector,
   investigator, lictor, lieutenant, mace-bearer, marshal,
   mounted policeman, officer, operative, patrolman, peace officer,
   peach, peacher, plainclothesman, police captain,
   police commissioner, police constable, police detective,
   police inspector, police matron, police officer, police sergeant,
   policeman, policewoman, portreeve, private detective,
   private investigator, rat, reeve, revenuer, roundsman, sell out,
   sergeant, sergeant at arms, sheriff, sleuth, snitch, snitch on,
   snitcher, spy, squeal, squealer, stool, stool pigeon, stoolie,
   store detective, superintendent, talebearer, tattle, tattler,
   tattletale, tell on, telltale, testify against, tipstaff,
   tipstaves, treasury agent, trooper, turn informer,
   whistle-blower

Narc >> N Words
Narc, definition of term: Narc
narc_pag1.html