Definition of "black box"

(informal, aviation) A flight recorder; the brightly colored cockpit voice recorders and flight data recorders in an aircraft designed to aid in determining the cause of an accident.  examples

(transport, by extension) Any similar device on motor vehicles, such as rail event recorders and ship trip recorders.  examples

A theoretical construct or device with known input and output characteristics but unknown method of operation.  examples

A device used in phreaking that prevents the calling party from being billed for the call placed.  examples

(drama) A type of theater characterized by a lack of decoration or complex mechanisms.  examples

(web development) To focus on the inputs and outputs without worrying about the internal complexity.  examples