In Greek mythology, Uranus (ˈjʊərənəs , also jʊˈreɪnəs ), sometimes written Ouranos (, uːranós), is the personification of the sky and one of the Greek primordial deities. According to Hesiod, Uranus was the son and husband of Gaia (Earth), with whom he fathered the first generation of Titans. However, no cult addressed directly to Uranus survived into Classical times, and Uranus does not appear among the usual themes of Greek painted pottery. Elemental Earth, Sky, and Styx might be joined, however, in solemn invocation in Homeric epic. Uranus is associated with the Roman god Caelus.
Most linguists trace the etymology of the name Οὐρανός to a Proto-Greek form *Worsanós (Ϝορσανός), enlarged from *ṷorsó- (also found in Greek οὐρέω (ouréō) 'to urinate', Sanskrit varṣá 'rain', Hittite ṷarša- 'fog, mist'). The basic Indo-European root is *ṷérs- 'to rain, moisten' (also found in Greek eérsē 'dew', Sanskrit várṣati 'to rain', or Avestan aiβi.varəšta 'it rained on'), making Ouranos the "rain-maker", or the "lord of rain".
A less likely etymology is a derivative meaning 'the one standing on high' from PIE *ṷérso- (cf. Sanskrit várṣman 'height, top', Lithuanian viršùs 'upper, highest seat', Russian verh 'height, top'). Of some importance in the comparative study of Indo-European mythology is the identification by Georges Dumézil (1934) of Uranus with the Vedic deity Váruṇa (Mitanni Aruna), god of the sky and waters, but the etymological equation is now considered untenable.
In Hesiod's Theogony, which came to be accepted by the Greeks as the "standard" account, from Gaia (Earth), the first entity to come into existence after Chaos (Void), came Uranus, the Ourea (Mountains), and Pontus (Sea).
Then, according to the Theogony, Uranus mated with Gaia, and she gave birth to the twelve Titans: Oceanus, Coeus, Crius, Hyperion, Iapetus, Theia, Rhea, Themis, Mnemosyne, Phoebe, Tethys and Cronus; the Cyclopes: Brontes, Steropes and Arges; and the Hecatoncheires ("Hundred-Handed Ones"): Cottus, Briareus, and Gyges.