Zeus (zs) KEY
Greek; see dyeu- in Indo-European roots
Homer's Iliad calls him "Zeus who thunders on high" and Milton's Paradise Lost, "the Thunderer," so it is surprising to learn that the Indo-European ancestor of Zeus was a god of the bright daytime sky. Zeus is a somewhat unusual noun in Greek, having both a stem Zn- (as in the philosopher Zeno's name) and a stem Di- (earlier Diw-). In the Iliad prayers to Zeus begin with the vocative form Zeu pater, "o father Zeus." Father Zeus was the head of the Greek pantheon; another ancient Indo-European society, the Romans, called the head of their pantheon Ipiter or IuppiterJupiter. The -piter part of his name is just a reduced form of pater, "father," and I- corresponds to the Zeu in Greek: Ipiter is therefore precisely equivalent to Zeu pater and could be translated "father Jove." Jove itself is from Latin Iov-, the stem form of Ipiter, an older version of which in Latin was Diov-, showing that the word once had a d as in Greek Diw-. An exact parallel to Zeus and Jupiter is found in the Sanskrit god addressed as Dyau pitar: pitar is "father," and dyau means "sky." We can equate Greek Zeu pater, Latin I-piter, and Sanskrit dyau pitar and reconstruct an Indo-European deity, *Dyus pter, who was associated with the sky and addressed as "father." Comparative philology has revealed that the "sky" word refers specifically to the bright daytime sky, as it is derived from the root meaning "to shine." This root also shows up in Latin dis "day," borrowed into English in words like diurnal.·Closely related to these words is Indo-European *deiwos "god," which shows up, among other places, in the name of the Old English god Tw in Modern English Tuesday, "Tiw's day." *Deiwos is also the source of Latin dvus "pertaining to the gods," whence English divine and the Italian operatic diva, and deus, "god," whence deity.