tattletale

from WordNet (r) 3.0 (2006)

tattletale
    n 1: someone who gossips indiscreetly [syn: {tattletale},
         {tattler}, {taleteller}, {talebearer}, {telltale},
         {blabbermouth}]

from Moby Thesaurus II by Grady Ward, 1.0

37 Moby Thesaurus words for "tattletale":
      a tale-bearing animal, betrayer, blab, blabber, blabberer,
      blabbermouth, busybody, delator, fink, gossip, gossip columnist,
      gossiper, gossipmonger, informer, narc, newsmonger, newspaperman,
      peacher, quidnunc, reporter, rumormonger, scandalmonger, snitch,
      snitcher, spy, squealer, stool pigeon, stoolie, tabby, talebearer,
      taleteller, tattler, telltale, tipster, tittle-tattler,
      whistle-blower, yenta