affidavit

noun

af·​fi·​da·​vit ˌa-fə-ˈdā-vət 

: a sworn statement in writing made especially under oath or on affirmation (see affirmation sense 2) before an authorized magistrate or officer

The witness's affidavit was presented to the court as evidence.

Did you know?

Promises, Promises: The History of Affidavit, Affiance, & Fiancé

Affidavit refers to a written promise, and its Latin roots connect it to another kind of promise in English. It comes from a past tense form of the Latin verb affidare, meaning “to pledge”; in Latin, affidavit translates to “he or she has made a pledge.”

Affidare is also the root of affiance, an archaic English noun meaning “trust, faith, confidence,” “marriage contract or promise,” or a meaning that has completely fallen from use, “close or intimate relationship.” More familiar to modern English speakers is the verb affiance, meaning “to promise in marriage” or “to betroth.” It usually appears as a fancy-sounding participial adjective:

I like to give affianced friends a copy of Rebecca Mead’s book “One Perfect Day,” which exposes the ridiculous wedding industry.
—Mollie Hemingway, The Federalist, 7 October 2014

Affiance came through French to English in the 14th century, and, nearly 500 years later, the related French words fiancé and fiancée were added to English. Etymologically speaking, a fiancé or fiancée is a “promised one.”

Did you know?

In Latin, affidavit means "he (she) has sworn an oath", and an affidavit is always a sworn written document. If it contains a lie, the person making it may be prosecuted. Affidavits are often used in court when it isn't possible for someone to appear in person. Police officers must usually file an affidavit with a judge to get a search warrant. Affidavits (unlike similar signed statements called depositions) are usually made without an opposing lawyer being present and able to ask questions.

Examples of affidavit in a Sentence

We have a signed affidavit stating that the two men were seen entering the building.

Recent Examples on the Web

The board then divided into two-person bipartisan teams to review 28 ballots with mismatched signatures where voters sent in affidavits to compare the signatures. —Alexandra Kukulka, Chicago Tribune, 14 May 2026

The woman was screaming and yelling for help on the call, KSL reported, citing a police booking affidavit. —Samira Asma-Sadeque, PEOPLE, 14 May 2026

In an arrest affidavit, the Metro Nashville Police Department reported Eatherly ordered two entrees, cocktails and appetizers totaling $371. —Natalie Neysa Alund, USA Today, 14 May 2026

The search-warrant affidavit that allowed the FBI to seize election materials in Georgia in January—an extraordinary intervention by federal law enforcement—cited an analysis by Parikh. —Shane Harris, The Atlantic, 14 May 2026

Word History

Etymology

borrowed from Medieval Latin affīdāvit "he/she has made a pledge," third person singular perfect indicative active of affīdāre — more at affiance entry 1

First Known Use

1515, in the meaning defined above

Kids Definition

affidavit

noun

af·​fi·​da·​vit ˌaf-ə-ˈdā-vət 

: a sworn statement in writing

Legal Definition

affidavit

noun

af·​fi·​da·​vit ˌa-fə-ˈdā-vət 

: a sworn statement in writing made especially under oath or on affirmation before an authorized magistrate or officer compare deposition, examination

Etymology

Medieval Latin, he/she has pledged faith, third singular perfect of affidare see affiant