black hole

WordReference Random House Learner's Dictionary of American English © 2025

ˈblack ˈhole, n. [countable]

1. Astronomy a large object in an area of space that has gravity so strong that no light or other radiation can escape from it:
   Black holes may have been formed at the beginning of the universe.

WordReference Random House Unabridged Dictionary of American English © 2025

black′ hole′, 

1. Astronomy a theoretical massive object, formed at the beginning of the universe or by the gravitational collapse of a star exploding as a supernova, whose gravitational field is so intense that no electromagnetic radiation can escape.

Black′ Hole′, 

1. World History Also called Black′ Hole′ of Cal•cut′ta. a small prison cell in Fort William, Calcutta, in which, in 1756, Indians are said to have imprisoned 146 Europeans, only 23 of whom were alive the following morning.
2. World History (l.c.) any usually wretched place of imprisonment or confinement.

Collins Concise English Dictionary © HarperCollins Publishers::

black hole noun

1. an object in space so dense that its escape velocity exceeds the speed of light
2. any place regarded as resembling a black hole in that items or information entering it cannot be retrieved