Chaos (derived from the Ancient Greek) typically means a state lacking order or predictability. In ancient Greece, it meant the initial state of the universe, and, by extension, space, darkness, or an abyss.

a state of extreme confusion and disorder…
the formless and disordered state of matter before the creation of the cosmos…
(Greek mythology) the most ancient of gods; the personification of the infinity of space preceding creation of the universe…
(physics) a dynamical system that is extremely sensitive to its initial conditions….