avowal vs averment

avowal and averment both are nouns.

Word	Noun	Adjective	Verb	Adverb
avowal	Yes	No	No	No
averment	Yes	No	No	No

As nouns, averment is a hypernym of avowal; that is, averment is a word with a broader meaning than avowal:

avowal: a statement asserting the existence or the truth of something
averment: a declaration that is made emphatically (as if no supporting evidence were necessary)

Other hypernyms of avowal include assertion, asseveration.

avowal (noun)	averment (noun)
a statement asserting the existence or the truth of something	a declaration that is made emphatically (as if no supporting evidence were necessary)