Chaos (Greek χάος, khaos) refers to the or void state preceding the creation of the universe or cosmos in the Greek creation myths, or to the initial "gap" created by the original separation of heaven and earth.
Greek means "emptiness, vast void, chasm, abyss", from the verb , "gape, be wide open, etc.", from Proto-Indo-European *ǵheh2n, cognate to Old English geanian, "to gape", whence English . It may also mean space, the expanse of air, and the nether abyss, infinite darkness.
Pherecydes of Syros (fl. 6th century BC) interpretes chaos as water, like something formless which can be differentiated.
Hesiod and the Pre-Socratics use the Greek term in the context of cosmogony. Hesiod's "chaos" has been interpreted as a moving, formless mass from which the cosmos and the gods originated. In Hesiod's opinion the origin should be indefinite and indeterminate, and it represents disorder and darkness.Chaos has been linked with the term tohu wa-bohu of Genesis 1:2. The term may refer to a state of non-being prior to creation or to a formless state. In the Book of Genesis, the spirit of God is moving upon the face of the waters, and the earliest state of the universe is like a "watery chaos". The Septuagint makes no use of χάος in the context of creation, instead using the term for גיא, "chasm, cleft", in Micah 1:6 and Zacharia 14:4.