From Longman Dictionary of Contemporary Englishgibbergib‧ber /ˈdʒɪbə $ -ər/ verb [intransitive] TALK TO somebodyto speak quickly in a way that is difficult to understand, especially because you are very frightened or shocked → jabbergibber with ‘It was her, ’ said Ruth, gibbering with fear. —gibbering adjective British English a gibbering wreck (=someone who is very shocked or frightened)→ See Verb table
Examples from the Corpus
gibber• Something else Hugh saw nearly made him gibber.• More voices began to call and gibber from other houses, and everywhere he saw signs that the familiar world was disintegrating.• He was gibbering with rage.a gibbering wreck• The great anti-Establishment provocateur of the Sixties now reduced to a gibbering wreck?Origin gibber (1600-1700) From the sound 