antagonist vs antagonistic

antagonist is a noun but antagonistic is not a noun.

Word	Noun	Adjective	Verb	Adverb
antagonist	Yes	No	No	No
antagonistic	No	Yes	No	No

antagonist (noun)	antagonistic (noun)
a drug that neutralizes or counteracts the effects of another drug
a muscle that relaxes while another contracts
someone who offers opposition

antagonist (adjective)	antagonistic (adjective)
	arousing animosity or hostility
	used especially of drugs or muscles that counteract or neutralize each other's effect
	characterized by antagonism or antipathy
	incapable of harmonious association
	indicating opposition or resistance