To prattle and chatter unintelligibly. (verb-intransitive)
Unintelligible or foolish talk. (noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "gibber" in a sentence
"Gazing out of windows is like watching TV for cats, but they never use teleprompters to "gibber" at birds."
"I even disregarded the fact that "gibber" is a verb, and not the noun "gibberish"."
"So to pick up on the theme of my previous post: if you'd care to be precise about what (in your opinion) constitutes "gibber" in my posts, I'd be only too happy to discuss it with you."