black box

American  

noun

1. any unit that forms part of an electronic circuit and that has its function, but not its components, specified.

2. any comparatively small, usually black, box containing a secret, mysterious, or complex mechanical or electronic device.

3. Aeronautics. an electronic device, such as a flight recorder, that can be removed from an aircraft as a single package.

4. Automotive. a device in an electronic ignition system that generates electrical pulses.

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black box British  

noun

1. a self-contained unit in an electronic or computer system whose circuitry need not be known to understand its function

2. an informal name for flight recorder

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black box Cultural  

1. A crash-resistant steel container that holds instruments that record performance data in airplanes. The data are used to analyze the causes of accidents.

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Etymology

Origin of black box

First recorded in 1940–45

Example Sentences

But her probe would be a black box that she could slow-walk indefinitely.

From Slate • Mar. 6, 2026

"Cat cancer genetics has totally been a black box up until now," said lead researcher, Dr Louise Van der Wayden.

From BBC • Feb. 19, 2026

The CPS said the Solong's black box showed no course or speed adjustments before the collision.

From Barron's • Feb. 2, 2026

Investigators have announced that the black box from the Army Black Hawk helicopter that collided with a commercial jetliner has been recovered.

From Los Angeles Times • Jan. 27, 2026

Finally, of course, my mother’s upraised hand is a kind of warning, too, a predecessor of the black box.

From "Middlesex: A Novel" by Jeffrey Eugenides