An affidavit is a written statement that you swear is true and that may be used as evidence in a court of law. An affidavit is a written statement which you swear is true and which may be used as evidence in a court of law.Affidavit definition: . This video shows you How to Pronounce Affidavit, pronunciation guide. The most popular dictionary and thesaurus for learners of English. Meanings and definitions of words with pronunciations and translations.