What do you call the region around a black hole from which nothing can escape?

The region around a black hole from which nothing can escape is known as the event horizon. This boundary is significant because it marks the point at which the gravitational pull of the black hole becomes so strong that the escape velocity exceeds the speed of light. When any matter or radiation crosses this threshold, it cannot return, leading to the concept that whatever enters this region is essentially lost to the outside universe. The event horizon plays a crucial role in our understanding of black holes and the nature of space and time, as it defines the limits of the black hole's influence and the point of no return for objects that approach it.

The singularity, on the other hand, refers to the point at the center of a black hole where density becomes infinitely high and the laws of physics as we know them break down, which is separate from the event horizon. The terms "black zone" and "gravity well" do not accurately describe the specific boundary around a black hole and are not standard terminology used in astrophysics.