WordReference Random House Unabridged Dictionary of American English © 2020
event hori′zon, [Astron.]
  1. Astronomythe boundary around a black hole on and within which no matter or radiation can escape.
  • 1970–75

Collins Concise English Dictionary © HarperCollins Publishers::
event horizon n
  1. the surface around a black hole enclosing the space from which electromagnetic radiation cannot escape due to gravitational attraction. For a non-rotating black hole, the radius is proportional to the mass of the black hole

Report an inappropriate ad.