babble vs blab out

babble is a noun but blab out is not a noun.

Word	Noun	Adjective	Verb	Adverb
babble	Yes	No	Yes	No
blab out	No	No	Yes	No

As verbs, babble and blab out are synonyms defined as:

Other synonyms of babble include babble out, blab, let the cat out of the bag, peach, sing, spill the beans, talk, tattle.

babble (noun)	blab out (noun)
gibberish resembling the sounds of a baby

babble (verb)	blab out (verb)
to talk foolishly	divulge confidential information or secrets
divulge confidential information or secrets
utter meaningless sounds, like a baby, or utter in an incoherent way
flow in an irregular current with a bubbling noise