antagonism vs oppositeness

antagonism and oppositeness both are nouns.

Word	Noun	Adjective	Verb	Adverb
antagonism	Yes	No	No	No
oppositeness	Yes	No	No	No

As nouns, oppositeness is a hypernym of antagonism; that is, oppositeness is a word with a broader meaning than antagonism:

Other hypernyms of antagonism include opposition.

antagonism (noun)	oppositeness (noun)
(biochemistry) interference in or inhibition of the physiological action of a chemical substance by another having a similar structure	the relation between opposed entities
an actively expressed feeling of dislike and hostility
the relation between opposing principles or forces or factors
a state of deep-seated ill-will