What term would best describe a written statement made under oath?

The term that best describes a written statement made under oath is "affidavit." An affidavit is a formal document in which an individual swears to the truth of the contents, often used in legal proceedings to establish facts and evidence. This sworn statement is typically signed by the person making the affidavit in the presence of a notary public or other authorized official, ensuring its authenticity and legal standing.

Affidavits play a significant role in legal matters because they provide a written record of a witness’s testimony, particularly when that testimony needs to be presented in court without the witness being physically present.

Other options such as 'affirmation' refer to a non-religious declaration made under oath, but it does not necessarily imply a written statement. 'Testimony' usually refers to oral statements made under oath during legal proceedings. Lastly, 'statement' is a more general term that does not specify the context of being sworn or legally binding. Thus, "affidavit" is the precise term that captures the essence of a written statement made under oath.