Deus (Latin pronunciation: [ˈdeːʊs]) is Latin for "god" or "deity". Latin deus and dīvus "divine", are descended from Proto-Indo-European *deiwos, "celestial" or "shining", from the same root as *Dyēus, the reconstructed chief god of the Proto-Indo-European pantheon. Compare Greek Zeus (Ζεύς dzeus; Aeolic Greek Δεύς deus) and Sanskrit देव deva. Latin ("day") is considered to have derived from the same PIE root that originated deus. This is to say that a celestial shining body, the Sun, gives material form to the words for "day" in the Romance Languages.
In Classical Latin, deus (feminine dea) was a general nounreferring to a deity, while in technical usage a divus or diva was a figure who had become divine, such as a divinized emperor. In Late Latin, Deus came to be used mostly for the Christian God. It was inherited by the Romance languages in French Dieu, Spanish Dios, Portuguese and Galician Deus, Italian Dio, etc., and by the Celtic languages in Welsh Duw and Irish Dia.