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

As well as the black box, Motability has introduced recommendations that drivers take a break every hour and aim not to do more than six journeys a day.

From BBC • Apr. 1, 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

After more than two decades, in 2025, the FDA walked back a black box warning requirement on HRT products that followed the 2002 study.

From The Wall Street Journal • Feb. 7, 2026

She opened the cabinet and pulled out a small black box with a combination lock on it.

From "Far from the Tree" by Robin Benway