Quick definitions from WordNet (attestant)
▸ noun: someone who affirms or vouches for the correctness or truth or genuineness of something
▸ noun: (law) a person who attests to the genuineness of a document or signature by adding their own signature
▸ noun: someone who affirms or vouches for the correctness or truth or genuineness of something
▸ noun: (law) a person who attests to the genuineness of a document or signature by adding their own signature