Editorial
Affidavit
Definition
A written statement of fact sworn or affirmed before a person authorised to administer oaths, used as evidence in court. A false statement in an affidavit may be perjury.
In plain English: A written statement you swear is true, which can be used as evidence.
A general definition, not tied to any jurisdiction. Check the meaning in the system that governs your matter before relying on it.