black box

1 of 2

noun

1

: a usually complicated electronic device whose internal mechanism is usually hidden from or mysterious to the user

broadly : anything that has mysterious or unknown internal functions or mechanisms

2

: a crashworthy device in aircraft for recording cockpit conversations and flight data

3

: a device in an automobile that records information (such as speed, temperature, or gasoline efficiency) which can be used to monitor vehicle performance or determine a cause in the event of an accident

black box

2 of 2

adjective

: being or containing a warning of a serious or life-threatening side effect (such as stroke or muscle damage) that is highlighted by a black border on a prescription drug's label or accompanying literature

Examples of black box in a Sentence

Noun

The black boxes were recovered from the crash site and provided useful information about the cause of the crash.

Recent Examples on the Web

Noun

Some of the biggest menopause news in recent years broke in November; the FDA removed the black box warning label, the agency’s highest warning classification for prescription drugs, from all hormone therapy treatments. —Helen Carefoot, Flow Space, 23 Dec. 2025

Clinton was also pictured relaxing in a hot tub next to a person whose face is redacted with a black box. —Swapna Venugopal Ramaswamy, USA Today, 22 Dec. 2025

Adjective

Makary said this during a recent press conference announcing that the FDA would, inexplicably, remove the black box warning on menopausal hormone therapy products that warned that these drugs could increase the risk of breast cancer, dementia, and heart attacks. —Patricia Bencivenga, STAT, 8 Jan. 2026

Charcoal gray, or even black, gives a small space a black box look, where there's no end in sight. —Heather Bien, Southern Living, 7 Jan. 2026

Word History

First Known Use

Noun

circa 1945, in the meaning defined at sense 1

Adjective

1968, in the meaning defined above

Rhymes for black box

• botox
• checkbox
• comox
• cornstalks
• cowpox
• crosswalks
• deadlocks
• detox
• feedstocks
• firebox
• gearbox
• hemlocks

Medical Definition

black box

adjective

: being or containing a warning of a serious or life-threatening side effect (as stroke, muscle damage, or suicidal tendencies) that is highlighted by a black border on a prescription drug's label or accompanying literature

A "black box" warning is the most serious warning placed in the labeling of a prescription medication.

—Johnathan D. Rockoff, The Fort Worth (Texas) Star-Telegram