- any unit that forms part of an electronic circuit and that has its function, but not its components, specified.
- any comparatively small, usually black, box containing a secret, mysterious, or complex mechanical or electronic device.
- Aeronautics. an electronic device, such as a flight recorder, that can be removed from an aircraft as a single package.
- Automotive. a device in an electronic ignition system that generates electrical pulses.
- a self-contained unit in an electronic or computer system whose circuitry need not be known to understand its function
- an informal name for flight recorder
1947, RAF slang for “navigational instruments;” later extended to any sort of apparatus that operates in a sealed container. Especially of flight recorders from c.1964.
A crash-resistant steel container that holds instruments that record performance data in airplanes. The data are used to analyze the causes of accidents.