"Black hole" (visual definition)

Cf. verbal definitions e.g. "A black hole is a region of space from which nothing, not even light, can escape.
Despite the name, they are not empty but instead consist of a huge amount of matter packed densely into a small area, giving it an immense gravitational pull.
There is a region of space beyond the black hole called the event horizon. This is a "point of no return", beyond which it is impossible to escape the gravitational effects of the black hole."
https://www.bbc.com/news/science-environment-47873592