affidavit
n. countablen. a written statement that you sign in front of a witness to prove it is true. You use this in legal matters when your word needs official weight.
n. a written statement of fact confirmed by oath or affirmation, typically used as evidence in legal proceedings.
She signed the affidavit to confirm her address.
The lawyer asked him to sign the affidavit before the court hearing began next week.
The judge dismissed the claim because the plaintiff failed to submit a sworn affidavit supporting the alleged damages.
From Medieval Latin affidavit (“he has sworn”), the third person singular perfect tense of affido (“swear”), from fīdō, ultimately from Proto-Indo-European *bʰeydʰ- (“to command, to persuade, to trust”). Cognate to fidelity and faith (same Latin root), but not to affirm (shared Latin ad- prefix, but different Latin and Proto-Indo-European roots).