event horizon

noun

: the surface of a black hole : the boundary of a black hole beyond which nothing can escape from within it

Examples of event horizon in a Sentence

Recent Examples on the Web

There’s one more factor that needs to be taken into account on the largest of cosmic scales, including for the cosmic measurements of the event horizon of the black hole at the center of galaxy Messier 87, and that is the expansion of the Universe. —Big Think, 25 Feb. 2026

Black holes are black because anything falling into them makes a one-way trip, after all; nothing, not even light, can escape once inside a black hole’s event horizon, its point of no return. —Phil Plait, Scientific American, 13 Feb. 2026

This crystal ball may be like a black hole with an event horizon, past which the light of its insight cannot escape. —Ross Andersen, The Atlantic, 11 Feb. 2026

In the new framework, information is not destroyed at the event horizon. —Rupendra Brahambhatt, Interesting Engineering, 17 Jan. 2026

Word History

First Known Use

1956, in the meaning defined above

Rhymes for event horizon

• mizen