*Dyēus

Dyḗus (lit. "daylight-sky-god"), also *Dyḗus ph2tḗr (lit. "father daylight-sky-god"), is the reconstructed name of the daylight-sky god in Proto-Indo-European mythology. *Dyēus was conceived as a divine personification of the bright sky of the day and the seat of the gods, the *deywṓs. Associated with the vast diurnal sky and with the fertile rains, *Dyēus was often paired with *Dhéǵhōm, the Earth Mother, in a relationship of union and contrast. While its existence is not directly attested by archaeological or written materials, *Dyēus is considered by scholars the most securely reconstructed deity of the Indo-European pantheon, as identical formulas referring to him can be found among the subsequent Indo-European languages and myths of the Vedic Indo-Aryans, Latins, Greeks, Phrygians, Messapians, Thracians, Illyrians, Albanians and Hittites. The divine name *Dyēus derives from the stem *dyeu-, denoting the "diurnal sky" or the "brightness of the day" (in contrast to the darkness of the night), ultimately from the root *di or dei- ("to shine, be bright"). Cognates in Indo-European languages revolving around the concepts of "day", "sky" and "deity" and sharing the root *dyeu- as an etymon, such as Sanskrit dyumán- 'heavenly, shining, radiant', suggest that Dyēus referred to the vast and bright sky of the day conceived as a divine entity among Proto-Indo-European speakers. A vṛddhi-derivative appears in *deywós ("celestial"), the common word for "god" in Proto-Indo-European. In classic Indo-European, associated with the late Khvalynsk culture (3900–3500), *Dyēus also had the meaning of "Heaven", whereas it denoted "god" in general (or the Sun-god in particular) in the Anatolian tradition. The suffix-derivative *diwyós ("divine") is also attested in Latin, Greek and Sanskrit. The noun *deynos ("day"), interpreted as a back-formation of *deywós, has descendant cognates in Vedic Sanskrit divé-dive ("day by day"), Latin Dies, goddess of the day and counterpart to Greek Hemera, Hittite siwat ("day"), Palaic Tīyat- ("Sun, day"), Ancient Greek endios ("midday"), Old Armenian tiw (տիւ, "bright day"), Old Irish noenden ("nine-day period"), Welsh heddyw ("today"), or Slavic Poludnitsa ("Lady Midday").