The herald of Manwë (S/30) who was at the forefront of the forces of the Valar when they marched to Beleriand to overthrow Morgoth for the final time (S/251). The final element of this name is the suffix -wë common in ancient names, but the meaning of the initial element is unclear.
Conceptual Development: In the earliest Lost Tales he was named ᴱQ. Fionwe and was the son of Manwë and Varda (LT1/58), and in the Qenya Lexicon from the 1910s its initial element is given as ᴱQ. fion “son” (QL/38). This character ᴹQ. Fionwe still appeared in Silmarillion drafts from the 1930s (LR/205) but in The Etymologies the gloss of its initial element is difficult to read, and could be either “hawk” or “haste” (Ety/PHI, WEG); Carl Hostetter and Patrick Wynne suggest that “hawk” is more likely (EtyAC/PHI). The character’s name and his relationship to Manwë did not change to that of Eonwë until Silmarillion revisions from the 1950s-60s (MR/146).
Eönwë masc. name, a Maia, herald of Manwë; a name evidently adopted and adapted from Valarin (WJ:417). In some sources the same character is called Fionwë, which would seem to be an Elvish form.