chat·ter 
(chătər)
(chătər)v. chat·tered, chat·ter·ing, chat·ters
v.intr.
1. To talk rapidly, incessantly, and on trivial subjects; jabber.
2. To utter a rapid series of short, inarticulate, speechlike sounds: birds chattering in the trees.
3. To click quickly and repeatedly: Our teeth chattered from the cold.
4. To vibrate or rattle while in operation: A power drill will chatter if the bit is loose.
v.tr.
To utter in a rapid, usually thoughtless way: chattered a long reply.
n.
1. Idle, trivial talk.
2. Communication, such as email and cell phone calls, between people who are involved in terrorism or espionage, as monitored by a government agency.
3. The sharp, rapid sounds made by some birds and animals.
4. A series of quick rattling or clicking sounds.
[Middle English chateren, of imitative origin.]
chatter·er n.