An affidavit is a sworn statement of fact that can be used in a variety of legal proceedings, from bankruptcy cases to family and civil litigation matters. Affirmation: A formal declaration that a statement is true.To lie is perjury and a person can be punished. For comprehensive definitions of legal terms, you may wish to consult a legal dictionary. An affidavit is a document where a person makes factual assertions, which they swear to be true and correct. A jury verdict that a criminal defendant is not guilty, or the finding of a judge that the evidence is insufficient to support a conviction. Com online Real Life Dictionary of the Law. What does Affidavit mean?