declarer vs asseverator

declarer and asseverator both are nouns.

Word	Noun	Adjective	Verb	Adverb
declarer	Yes	No	No	No
asseverator	Yes	No	No	No

As nouns, declarer and asseverator are synonyms defined as:

Other synonyms of declarer include affirmer, asserter, avower.

declarer (noun)	asseverator (noun)
the bridge player in contract bridge who wins the bidding and can declare which suit is to be trumps	someone who claims to speak the truth
someone who claims to speak the truth