blabbermouth

from WordNet (r) 3.0 (2006)

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

from The Collaborative International Dictionary of English v.0.48

blabbermouth \blabbermouth\ n.
   someone who gossips indiscreetly.

   Syn: blabber, tattletale, taleteller, talebearer, telltale.
        [WordNet 1.5]

from Moby Thesaurus II by Grady Ward, 1.0

28 Moby Thesaurus words for "blabbermouth":
      babbler, betrayer, blab, blabber, blabberer, chatterer, delator,
      fink, gabber, gossip, informer, jabberer, magpie, narc, peacher,
      prater, prattler, snitch, snitcher, spy, squealer, stool pigeon,
      stoolie, talebearer, tattler, tattletale, telltale,
      whistle-blower

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