Merriam-Webster's Collegiate® Dictionary, 11th Edition
JABBER
I. verb (jabbered; jabbering)
Etymology: Middle English jaberen, of imitative origin
Date: 15th century
intransitive verb to talk rapidly, indistinctly, or unintelligibly, transitive verb to speak rapidly or indistinctly, jabberer noun
II. noun
Date: 1708
gibberish , chatter