Event horizon

/əˈvɛnt həˈɹaɪ.zən/ noun

noun ·Rare ·Advanced level

Definitions

Noun
  1. 1
    The gravitational sphere of a black hole within which the escape velocity is greater than the speed of light.
  2. 2
    The furthest distance in the past of the universe from which light signals from an event can reach an observer at later times.
  3. 3
    A point of no return. broadly, figuratively