gibber vs meaninglessness

gibber and meaninglessness both are nouns.

Word	Noun	Adjective	Verb	Adverb
gibber	Yes	No	Yes	No
meaninglessness	Yes	No	No	No

As nouns, meaninglessness is a hypernym of gibber; that is, meaninglessness is a word with a broader meaning than gibber:

Other hypernyms of gibber include bunk, hokum, nonsense, nonsensicality.

gibber (noun)	meaninglessness (noun)
unintelligible talking	the quality of having no value or significance
	a message that seems to convey no meaning

gibber (verb)	meaninglessness (verb)
speak (about unimportant matters) rapidly and incessantly
chatter inarticulately; of monkeys