ell (from CE *eldā- connected or concerned with the stars) + adan (“a man from one of the three houses of the Edain”)
Sindarin
elladan
masculine name. Elf-man
Elladan
noun. elf-man
adanedhel
masculine name. Elf-man
ellon
noun. Elf-man
ellon
elf-man
ellon (pl. ellyn),
ellon
elf-man
ellon (pl. ellyn) (WJ:363-64, 377).
Son of Elrond (LotR/227). This name is translated “Elf-man”, a combination of archaic Sindarin †Ell “elf” and Adan “man” (Let/281-2).
Conceptual Development: In Lord of the Rings drafts from the 1940s, this character was first named N. Elboron (WR/297). Earlier still, the name Ilk. Elboron used as a name for a son of Dior (LR/147).