The name of the 4th king of Arnor and the 21st kings of Gondor (LotR/1038), it is a compound of Elda “Elf” and the suffixal form -car of carma “helm”.
Conceptual Development: In the draft versions of The Lord of the Rings, ᴹQ. Eldakar was considered as a name for Aragorn’s father, where it was glossed “Elfhelm” (TI/366). An even earlier precursor of the name appears in The Etymologies: ᴹQ. Eldahar, where the second element is derived from the root ᴹ√KHAR “helmet” (EtyAC/KHAR).
Eldacar masc. name, *"Elfhelm". Compare carma "helmet". (Appendix A)