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

Imagine opening a black box, only to find 5,000 more black boxes inside.

From The Wall Street Journal • Mar. 16, 2026

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

From Slate • Mar. 6, 2026

Instead, it stages work in unlikely spaces: Masonic lodges, American Legions, women’s centers, but never traditional black box theaters.

From Los Angeles Times • Mar. 2, 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

A sweetness gathered in his breast as he saw the room being turned into a shambles, a sweet moment of triumph that compensated for all the other lousy things, his terrible marks, the black box.

From "The Chocolate War" by Robert Cormier