"event horizon" ("point of no return") most commonly associated with black holes

Credit: Evolution News

In general relativity, an event horizon is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms, it is defined as "the point of no return", i.e., the point at which the gravitational pull becomes so great as to make escape impossible, even for light. An event horizon is most commonly associated with black holes. - wikipedia