black box

1. The device in an airplane that records flight audio and data. Once the black box is recovered from the wreckage, it will give us more insight into what caused the crash. Did the recordings from the black box illuminate anything about the incident? The plane exploded, though. Will they still be able to get information from the black box?

2. Any sort of system or device with inner workings that are difficult to understand. Does anyone outside of the IT department really understand how this black box works? Do you know what is going on with that black box? Why does it beep intermittently like that? I asked the manager how to open this black box, and he had no idea either.

a black box

You can call a process or system a black box when you know that it produces a particular result but you do not understand how it works. What steroids do is currently something of a black box. The firm's investment success lies in its black box of formulas which identify trends. Note: In an electronic or computer system, a black box is a self-contained part. You can understand its function without knowing anything about how it works.

black box

an automatic apparatus, the internal operations of which are mysterious to non-experts.

Black does not refer to the colour of the device but to the arcane nature of its functions. Originally Royal Air Force slang for a navigational instrument in an aircraft, the phrase is now used in aviation specifically to refer to the flight recorder.