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event horizon

noun, Astronomy
1.
the boundary around a black hole on and within which no matter or radiation can escape.
Origin
1970-1975
1970-75
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for event-horizon

event horizon

noun
1.
(astronomy) 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
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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event-horizon in Science
event horizon
  (ĭ-věnt')   
A spatial boundary around a black hole inside which gravity is strong enough to prevent all matter and radiation from escaping. The inability of even light to escape this region is what gives black holes their name.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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