A name of Aragorn (LotR/375), a compound of elen “star” and sar “stone”. The final -n of elen was assimilated to the s, which also happened in the name Elestirnë. The name was glossed “Elfstone”, no doubt due to the association of the words elen “star” and Elda “Elf”. A similar confusion is seen in the name Elendil “Elf-friend” (properly “Star-lover”).
Conceptual Development: As a name for Aragon, this name first appeared in Lord of the Rings drafts from the 1940s as ᴹQ. Eldamir with the variant Qendemir (TI/276). It was soon changed to ᴹQ. Elessar (TI/294) and kept that form thereafter. Tolkien also considered using Elessar for the name of the last king of Gondor, before changing that name to Eärnur (WR/153).
Elessar masc. name "Elf-stone" (Elen + sar, actually "Star-stone", cf. Elendil concerning elen "star" being used to mean "Elf") (LotR3:V ch. 8). Genitive Elesarno _(VT49:28, read _Elessarno?) indicates that the stem is -sarn-. As a common noun, elessar or "elf-stone" may signify "beryl" (in the chapter Flight to the Ford in the LotR, Aragorn finds "a single pale-green jewel" and declares: "It is a beryl, an elf-stone"). Elessar as a name may also be seen as a pun or variant of Elesser "Elf-friend".