A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court.Affidavit definition: . See examples of AFFIDAVIT used in a sentence. An affidavit is a written statement that you swear is true and that may be used as evidence in a court of law. Complete the affidavit of candidacy. In order to file for office, you need to fill out an affidavit of candidacy (PDF, 1MB). Both copies will be required in court. This guide is a reference for election judges on. That I am fluent in both English and . 2.