Chaos (erived from the Ancient Greek Χάος, Chaos) typically refers to unpredictability, and is the antithetical concept of cosmos. The word χάος did not mean "disorder" in classical-period ancient Greece. It meant "the primal emptiness, space" (see Chaos (mythology)). Chaos is derived from the Proto-Indo-Euopean root ghn or ghen meaning "gape, be wide open": compare "chasm" (from Ancient Greek χάσμα, a cleft, slit or gap), and Anglo-Saxon gānian ("yawn"), geanian, ginian ("gape wide"); see also Old Norse Ginnungagap. Due to people misunderstanding early Christian uses of the word, the meaning of the word changed to "disorder". (The Ancient Greek for "disorder" is ταραχή.).