accusation vs asseveration

accusation and asseveration both are nouns.

Word	Noun	Adjective	Verb	Adverb
accusation	Yes	No	No	No
asseveration	Yes	No	No	No

As nouns, asseveration is a hypernym of accusation; that is, asseveration is a word with a broader meaning than accusation:

accusation: an assertion that someone is guilty of a fault or offence
asseveration: a declaration that is made emphatically (as if no supporting evidence were necessary)

Other hypernyms of accusation include assertion, averment.

accusation (noun)	asseveration (noun)
a formal charge of wrongdoing brought against a person; the act of imputing blame or guilt	a declaration that is made emphatically (as if no supporting evidence were necessary)
an assertion that someone is guilty of a fault or offence