If a black hole is so dense wouln't it be solid and not a hole at all?

Answer 1

Black holes do indeed have a central singularity of infinite density and zero volume where all mass in concentrated; however, the term "solid" describes a state of matter which definition may defy the unclearly described and poorly understood state of matter in the singularity.

Despite the apt metaphor of being a "hole" into which matter and energy can disappear never to return, black holes are not strictly speaking a hole in the common sense; in fact, it might be better described as an unusual region of spacetime answering to infinite spatial or temporal curvature as described by Einstein's General Relativity than it would either as a hole or as a material object.

Answer 2

A black hole is called a "hole" because it has a gravitational pull strong enough to prevent anything, including light, from escaping. It is not a physical hole in the traditional sense. The extreme density of a black hole causes matter to collapse to a singularity, a location where the laws of physics, as we currently understand them, break down.