The Collaborative International Dictionary of English v.0.48:

Tattle \Tat"tle\, v. i. [imp. & p. p. Tattled; p. pr. & vb. n.
   Tattling.] [Akin to OE. tateren, LG. tateln, D. tateren to
   stammer, and perhaps to E. titter.]
   1. To prate; to talk idly; to use many words with little
      meaning; to chat.
      [1913 Webster]

            The tattling quality of age, which is always
            narrative.                            --Dryden.
      [1913 Webster]

   2. To tell tales; to communicate secrets; to be a talebearer;
      as, a tattling girl.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Tattle \Tat"tle\, n.
   Idle talk or chat; trifling talk; prate.
   [1913 Webster]

         [They] told the tattle of the day.       --Swift.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tattle
    n 1: disclosing information or giving evidence about another
         [syn: tattle, singing, telling]
    v 1: speak (about unimportant matters) rapidly and incessantly
         [syn: chatter, piffle, palaver, prate, tittle-
         tattle, twaddle, clack, maunder, prattle, blab,
         gibber, tattle, blabber, gabble]
    2: divulge confidential information or secrets; "Be careful--his
       secretary talks" [syn: spill the beans, let the cat out of
       the bag, talk, tattle, blab, peach, babble,
       sing, babble out, blab out] [ant: keep one's mouth
       shut, keep quiet, shut one's mouth]

Moby Thesaurus II by Grady Ward, 1.0:

74 Moby Thesaurus words for "tattle":
   babble, back-fence gossip, be indiscreet, be unguarded,
   bear witness against, betray, betray a confidence, blab, blabber,
   blather, blether, blow the whistle, blurt, blurt out, buzz,
   chatter, chitchat, clatter, cry, divulge, fink, give away, gossip,
   gossiping, gossipmongering, gossipry, grapevine, groundless rumor,
   hearsay, idle talk, inform, inform against, inform on, jabber,
   leak, let drop, let fall, let slip, narc, natter, newsmongering,
   peach, piece of gossip, prate, prattle, rat, retail gossip, reveal,
   reveal a secret, rumble, rumor, scuttlebutt, sell out, sing,
   snitch, snitch on, spill, spill the beans, squeal, stool, story,
   tale, talebearing, taletelling, talk, tattle on, tell,
   tell idle tales, tell on, tell secrets, tell tales,
   testify against, tittle-tattle, turn informer