Singularity is the starting point of the evolution of the universe traced by the Big Bang cosmology, or the point in the center of a black hole. The density of the singularity is infinite, and so is the curvature of spacetime at the singularity. Singularity has a series of strange properties, such as infinite density of matter, infinite bending of time and space, and infinite entropy approaching zero.
Singularity is usually an undefined point on a mathematical object, or when it can't be sorted under special circumstances, it makes this point appear in the abnormal set. For the real function f (x) = h (x)/g(x), the zero point x=a of g(x) is mathematically called a singularity.