The Collaborative International Dictionary of English v.0.48:

Chatter \Chat"ter\, v. i. [imp. & p. p. Chattered; p. pr. &
   vb. n. Chattering.] [Of imitative origin. Cf. Chat, v. i.
   Chitter.]
   1. To utter sounds which somewhat resemble language, but are
      inarticulate and indistinct.
      [1913 Webster]

            The jaw makes answer, as the magpie chatters.
                                                  --Wordsworth.
      [1913 Webster]

   2. To talk idly, carelessly, or with undue rapidity; to
      jabber; to prate.
      [1913 Webster]

            To tame a shrew, and charm her chattering tongue.
                                                  --Shak.
      [1913 Webster]

   3. To make a noise by rapid collisions.
      [1913 Webster]

            With chattering teeth, and bristling hair upright.
                                                  --Dryden.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chattering \Chat"ter*ing\, n.
   The act or habit of talking idly or rapidly, or of making
   inarticulate sounds; the sounds so made; noise made by the
   collision of the teeth; chatter.
   [1913 Webster]

WordNet (r) 3.0 (2006):

chattering
    n 1: the rapid series of noises made by the parts of a machine
         [syn: chatter, chattering]
    2: the high-pitched continuing noise made by animals (birds or
       monkeys) [syn: chatter, chattering]