1. To converse in an easy, familiar manner; talk lightly and casually.
2. Computer Science. To participate in a synchronous exchange of remarks with one or more people over a computer network.

1. An informal, light conversation.
2. Computer Science. A synchronous exchange of remarks over a computer network.
3. Any of several birds known for their chattering call, as of the genera Saxicola or Icteria.

chat up

1. To engage (someone) in light, casual talk: "He would be . . . chatting up folks from Kansas" (Vanity Fair).

[Middle English chatten, to jabber, alteration of chateren. See chatter.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.