DuckCorp Dico

Found one definition

1.                 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]