A theoretical construct or device with known input and output characteristics but unknown method of operation.
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.
A device used in phreaking that prevents the calling party from being billed for the call placed.
A type of theater characterized by a lack of decoration or complex mechanisms.
Any similar device on motor vehicles, such as rail event recorders and ship trip recorders.
To focus on the inputs and outputs without worrying about the internal complexity.
The quality of being able to achieve one's aims through clever, delicate or indirect methods.
The quality of being done in a clever way that is not obvious or not direct; the quality of being carefully thought out.
The quality of being able to notice or understand things that are not obvious.
An instance of being subtle, a subtle thing, especially a subtle argument or distinction.
The quality of being scarcely noticeable or difficult to discern.
An ornate medieval illusion dish or table decoration, especially when made from one thing but crafted to look like another.