Noun. US. Early 19th century.
[Old French afier, (later aff-) from medieval Latin affidare to trust]
LAW. A person who makes an affidavit.
I always like finding out I'm something that I didn't know I was. Specifically, I didn't know I was an affiant. As someone that worked closely with the legal profession for ten years, I regularly had to make affidavits; therefore, I was an affiant. It also has a rather charming etymology. Nice.