babble vs sing

babble is a noun but sing is not a noun.

Word	Noun	Adjective	Verb	Adverb
babble	Yes	No	Yes	No
sing	No	No	Yes	No

As verbs, babble and sing are synonyms defined as:

babble (noun)	sing (noun)
gibberish resembling the sounds of a baby

babble (verb)	sing (verb)
to talk foolishly	make a whining, ringing, or whistling sound
divulge confidential information or secrets	divulge confidential information or secrets
utter meaningless sounds, like a baby, or utter in an incoherent way	to make melodious sounds
flow in an irregular current with a bubbling noise	produce tones with the voice
	deliver by singing