From Greek 'khaos' (yawning void), from PIE *gheh2- (to gape) — originally the primordial emptiness before creation.
Complete disorder and confusion; the formless matter supposed to have existed before the creation of the universe.
From Latin 'chaos,' from Greek 'kháos' (χάος, vast chasm, void, the primeval emptiness before creation), from PIE *ǵʰeh₂- (to gape, to yawn, to open wide). The original meaning was not 'disorder' but 'yawning void' — the infinite gap that existed before the gods shaped the cosmos. Hesiod's Theogony begins: 'First of all, Chaos came into being.' The shift from 'primordial void' to 'disorder'
The word 'gas' was invented in the 1640s by the Flemish chemist Jan Baptist van Helmont, who modeled it directly on Greek 'kháos' (chaos) — he saw gases as formless, chaotic substances. So every time you say 'gas,' you are speaking a seventeenth-century scientist's personal tribute to Hesiod's primordial void.