expectorate vs sputter

expectorate is not a noun while sputter is a noun.

Word	Noun	Adjective	Verb	Adverb
expectorate	No	No	Yes	No
sputter	Yes	No	Yes	No

As verbs, sputter is a hyponym of expectorate; that is, sputter is a word with a more specific, narrower meaning than expectorate:

expectorate: discharge (phlegm or sputum) from the lungs and out of the mouth
sputter: spit up in an explosive manner

Other hyponyms of expectorate include cough, ptyalise, ptyalize, spew, spit, spue, spit out, splutter.

expectorate (noun)	sputter (noun)
	an utterance (of words) with spitting sounds (as in rage)
	the noise of something spattering or sputtering explosively

expectorate (verb)	sputter (verb)
discharge (phlegm or sputum) from the lungs and out of the mouth	spit up in an explosive manner
clear out the chest and lungs	cause to undergo a process in which atoms are removed
	utter with a spitting sound, as if in a rage
	climb awkwardly, as if by scrambling
	make an explosive sound