The Collaborative International Dictionary of English v.0.48:

Babble \Bab"ble\ (b[a^]b"b'l), v. i. [imp. & p. p. Babbled
   (b[a^]b"b'ld); p. pr. & vb. n. Babbling.] [Cf. LG. babbeln,
   D. babbelen, G. bappeln, bappern, F. babiller, It. babbolare;
   prob. orig., to keep saying ba, imitative of a child learning
   to talk.]
   1. To utter words indistinctly or unintelligibly; to utter
      inarticulate sounds; as a child babbles.
      [1913 Webster]

   2. To talk incoherently; to utter unmeaning words.
      [1913 Webster]

   3. To talk much; to chatter; to prate.
      [1913 Webster]

   4. To make a continuous murmuring noise, as shallow water
      running over stones.
      [1913 Webster]

            In every babbling brook he finds a friend.
                                                  --Wordsworth.
      [1913 Webster]

   Note: Hounds are said to babble, or to be babbling, when they
         are too noisy after having found a good scent.
         [1913 Webster]

   Syn: To prate; prattle; chatter; gossip.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Babble \Bab"ble\, v. t.
   1. To utter in an indistinct or incoherent way; to repeat, as
      words, in a childish way without understanding.
      [1913 Webster]

            These [words] he used to babble in all companies.
                                                  --Arbuthnot.
      [1913 Webster]

   2. To disclose by too free talk, as a secret.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Babble \Bab"ble\, n.
   1. Idle talk; senseless prattle; gabble; twaddle. "This is
      mere moral babble." --Milton.
      [1913 Webster]

   2. Inarticulate speech; constant or confused murmur.
      [1913 Webster]

            The babble of our young children.     --Darwin.
      [1913 Webster]

            The babble of the stream.             --Tennyson.
      [1913 Webster]

WordNet (r) 3.0 (2006):

babble
    n 1: gibberish resembling the sounds of a baby [syn: babble,
         babbling, lallation]
    v 1: utter meaningless sounds, like a baby, or utter in an
         incoherent way; "The old man is only babbling--don't pay
         attention"
    2: to talk foolishly; "The two women babbled and crooned at the
       baby" [syn: babble, blather, smatter, blether,
       blither]
    3: flow in an irregular current with a bubbling noise; "babbling
       brooks" [syn: ripple, babble, guggle, burble,
       bubble, gurgle]
    4: 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:

199 Moby Thesaurus words for "babble":
   Aesopian language, Babel, Greek, absurdity, amphigory, argot,
   babblement, baffle, balderdash, bavardage, be Greek to,
   be beyond one, be indiscreet, be insane, be too deep, be unguarded,
   beat one, betray, betray a confidence, bibble-babble, blab,
   blabber, blah-blah, blather, blether, blethers, blurt, blurt out,
   bombast, bubble, bull, bullshit, burble, cackle, cant, caquet,
   caqueterie, chat, chatter, chattering, chitchat, chitter-chatter,
   cipher, clack, claptrap, clatter, code, cryptogram, disclose,
   dither, divulge, dote, double Dutch, double-talk, drivel, drool,
   escape one, fiddle-faddle, fiddledeedee, flummery, folderol, fudge,
   fustian, gab, gabble, galimatias, gammon, garble, gas, gibber,
   gibberish, gibble-gabble, gift of tongues, give away, glossolalia,
   go on, gobbledygook, gossip, guff, guggle, gurgle, gush,
   have a demon, haver, hocus-pocus, hot air, hubbub, humbug,
   idle talk, inform, inform on, jabber, jabberwocky, jargon, jaw,
   jumble, lap, leak, let drop, let fall, let slip, lose one,
   mere talk, mumbo jumbo, murmur, narrishkeit, natter,
   need explanation, niaiserie, noise, nonsense, nonsense talk,
   not make sense, not penetrate, pack of nonsense, palaver,
   pass comprehension, patter, peach, perplex, piffle, plash,
   pour forth, prate, prating, prattle, prittle-prattle, purl, rabbit,
   rage, ramble, ramble on, rant, rat, rattle, rattle on, rave,
   reel off, repeat, reveal, reveal a secret, riddle, rigamarole,
   rigmarole, ripple, rodomontade, rubbish, run amok, run mad, run on,
   scramble, secret language, sing, skimble-skamble, slang, slaver,
   slobber, slosh, speak in tongues, spill, spill the beans, splash,
   spout, spout off, squeal, stool, stuff and nonsense,
   stultiloquence, swash, swish, talk, talk away, talk double Dutch,
   talk nonsense, talk on, talkee-talkee, tattle, tattle on, tell,
   tell on, tell secrets, tell tales, tittle-tattle, trash, trill,
   trumpery, twaddle, twattle, twiddle-twaddle, vapor, vaporing,
   waffle, waffling, wander, wash, yak, yakkety-yak, yammer, yap