headbutt vs bunt

headbutt is not a noun while bunt is a noun.

Word	Noun	Adjective	Verb	Adverb
headbutt	No	No	Yes	No
bunt	Yes	No	Yes	No

As verbs, bunt is a hypernym of headbutt; that is, bunt is a word with a broader meaning than headbutt:

Other hypernyms of headbutt include butt.

headbutt (noun)	bunt (noun)
	(baseball) the act of hitting a baseball or softball lightly by holding the bat in a stationary position rather than swinging it
	fungus that destroys kernels of wheat by replacing them with greasy masses of smelly spores
	similar to Tilletia caries
	disease of wheat characterized by replacement of the grains with greasy masses of smelly smut spores

headbutt (verb)	bunt (verb)
butt with the head	to strike, thrust or shove against
	hit a ball in such a way so as to make it go a short distance