jabber vs rabbit on

jabber is a noun but rabbit on is not a noun.

Word	Noun	Adjective	Verb	Adverb
jabber	Yes	No	Yes	No
rabbit on	No	No	Yes	No

As verbs, jabber and rabbit on are synonyms defined as:

Other synonyms of jabber include mouth off, rant, rave, spout.

jabber (noun)	rabbit on (noun)
rapid and indistinct speech

jabber (verb)	rabbit on (verb)
talk in a noisy, excited, or declamatory manner	talk in a noisy, excited, or declamatory manner