witness vs attestant

witness and attestant both are nouns.

Word	Noun	Adjective	Verb	Adverb
witness	Yes	No	Yes	No
attestant	Yes	No	No	No

As nouns, attestant is a hyponym of witness; that is, attestant is a word with a more specific, narrower meaning than witness:

witness: someone who sees an event and reports what happened
attestant: someone who affirms or vouches for the correctness or truth or genuineness of something

Other hyponyms of witness include attester, deponent, deposer, testifier.

As nouns, witness and attestant are synonyms defined as:

witness and attestant: (law) a person who attests to the genuineness of a document or signature by adding their own signature

Other synonyms of witness include attestator, attestor.

witness (noun)	attestant (noun)
testimony by word or deed to your religious faith	(law) a person who attests to the genuineness of a document or signature by adding their own signature
someone who sees an event and reports what happened	someone who affirms or vouches for the correctness or truth or genuineness of something
a close observer; someone who looks at something (such as an exhibition of some kind)
(law) a person who attests to the genuineness of a document or signature by adding their own signature
(law) a person who testifies under oath in a court of law

witness (verb)	attestant (verb)
be a witness to
perceive or be contemporaneous with