A written statement that someone makes after promising officially to tell the truth. An affidavit can be used as proof in a law court.The term is pronounced as "afuhDAYvit. " Breaking it down: "af" as in "after," "uh" as in "umbrella," "DAY" with emphasis, and "vit" rhymes with "fit." A written declaration upon oath made before an authorized official. No information is available for this page. This video shows you How to Pronounce Affidavit, pronunciation guide. How to pronounce AFFIDAVIT. How to say AFFIDAVIT.