Zeus: The principal god of the Greek pantheon, ruler of the heavens, and father of other gods and mortal heroes
[Greek. See dyeu- in Indo-European Roots.]
Word History: 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 Z n- (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 I piter or Iuppiter (Jupiter). The -piter part of his name is just a reduced form of pater, “father,” and I - corresponds to the Zeu in Greek: I piter is therefore precisely equivalent to Zeu pater and could be translated “father Jove.” Jove itself is from Latin Iov-, the stem form of I piter, 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, *Dy us p ter, 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 di s “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 (Norse) god T w in Modern English Tuesday, “Tiw's day.” *Deiwos is also the source of Latin d vus “pertaining to the gods,” whence English divine and the Italian operatic diva, and deus, “god,” whence deity.
Manwë: The Ruler of the Valar
Word History: Manwë, see Mánir. The Gnomish names are Man and Manweg (for –weg see Bronweg). [Under Bronweg, we see the comment, “The common ending –weg is not given in GL (Gnomish Lexicon), but cf. gweg ‘man’, plural gwaith.] Going to Manir, we see, Not in QL (Quenta Lexicon); but GL has ‘móna or móni: the spirits of the air, children of Manweg’. Further relations are indicated in the following entry: ‘manos (plural manossin): a spirit that has gone to the Valar or to Erumani (Edhofon). Cf. mona, Q. manë.’ See Eruman. Other words are mani ‘good (of men and character only), holy ‘ (QL manë ‘good (moral)’), mandra ‘noble’, and Manweg (Q. Manwë).
from Appendix ‘Names in the Lost Tales’ in The Book of Lost Tales, by J.R.R.Tolkien, p. 280.
Commentary by Squire
Thus a root definition for Manwë might be 'Spirit-man', as a single being who embodies spirituality, holiness, goodness. If we substitute "God" for "Spirit" (Manë-), and substitute "-father" for "-man" (-weg) in this case, as in "Original Man" (Adam is known as "Father Adam") or "Father, or Type, of all men", we get a close correspondence between Greek "zeu pater"/Roman "iu piter"/Sanskrit "dyau pitar"/IndoEuropean "dy us p ter"=Sky or God Father, and Quenta "manweg" or Manwë=God Father.
Although Tolkien does not connect root Manë- with the sky, as IndoEuropean does with *Dy us leading both to English "day, diurnal, diary" and "divine, deity", I believe it is no coincidence that it is Manwë who happens to "delight ... in the winds and the clouds".