gibbering

"Fahrenheit 451" を読んでいますが、国民が本を所有してはいけないという未来のユニーク過ぎる設定であることと、描写が非常に比喩的なのでとても難しく感じる内容です。とりあえず表面的な意味だけでも理解することにします。
Well, wasn't there a wall between him and Mildred, when you came down to it? Literally not just one wall but, so far, three! And expensive, too! And the uncles, the aunts, the cousins, the nieces, the nephews, that lived in those walls, the gibbering pack of tree-apes that said nothing, nothing, nothing and said it loud, loud.
何も言わないのに大声とはチンプンカンプンです。そこは無視して、何か見覚えのある "gibbering" の意味を調べます。
・Macmillan Dictionary: unable to speak in a sensible way, especially because you are frightened or shocked: After a day with the kids I'm a gibbering wreck.
次ぎの二つの辞書を含め、普通は "gibber" の項目で動詞としての説明を載せています。
・Collins Dictionary: 1.to utter rapidly and unintelligibly; prattle 2.(intransitive) (of monkeys and related animals) to make characteristic chattering sounds: Their first response was to hide completely, leaving Sir Norman Fowler and poor Tim Smith to squeak and gibber on the television.
・Cambridge English Dictionary: to speak quickly in a way that cannot be understood, usually when you are very frightened or confused: Stop gibbering, man, and tell us what you saw.
フムフム、以前 "gibberish" を採り上げたのを思い出しました。ジュニア小説に出てきた単語なので "gibber" は英米人なら子供でも知っている単語なのでしょう。