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.
1. To utter sounds which somewhat resemble language, but are
inarticulate and indistinct.
The jaw makes answer, as the magpie chatters.
2. To talk idly, carelessly, or with undue rapidity; to
jabber; to prate.
To tame a shrew, and charm her chattering tongue.
3. To make a noise by rapid collisions.
With chattering teeth, and bristling hair upright.