Eldo noun, archaic variant of Elda, properly one of the "Marchers" from Cuiviénen, but the word went out of use (WJ:363, 374)
Quenya
eldo
proper name. one of the Marchers
Eldo
marchers
elda
of the stars
elda 1. originally adj. "of the stars", but wholly replaced (WJ:362) by: 2. noun (Elda) = one of the people of the Stars, (high-)elf, an Elf (SA:êl, elen, Letters:281, ELED, ÉLED; notice that Tolkien abandoned a former etymology with "depart"), chiefly in the pl. Eldar (WJ:362, cf. GAT(H), TELES).The primitive form Tolkien variously cited as ¤eledā / elenā(Letters:281, PE17:152) and ¤eldā(WJ:360). Partitive pl. Eldali (VT49:8), gen. pl. Eldaron (WJ:368, PM:395, 402);dative pl.eldain "for elves", for Eldar (FS); possessive sg. Eldava "Elf's" (WJ:407); possessive pl. Eldaiva (WJ:368), Eldaivë governing a plural word (WJ:369). The word Eldar properly refers to the non-Avari Elves only, but since Eldar rarely had any contact with the Avari, it could be used for "elves" in general (in LT1:251, Elda is simply glossed "Elf"). See also Eldo. The plural form Eldar should not require any article when the reference is to the entire people; i Eldar refers to a limited group, "(all) the Elves previously named"; nevertheless, Tolkien in some sources does use the article even where the reference seems to be generic (i Eldar or i-Eldar, VT49:8).
elena
of the stars
elena adj. "of the stars" (SA:êl, elen); also elenya
sinda eldō
a Grey Elf’s
An archaic variant of Elda “Elf” meaning “Marcher”, as in “those who marched to Valinor”. It was derived from the root √DEL “walk, travel” by inversion of its letters: ✶edelō > eledo > Eldo (WJ/363). It fell out of use in Quenya and was replaced (blended with) Elda (WJ/374), but it survived in Sindarin as the primary word for Elf: S. Edhel (WJ/364).
Conceptual Development: This was a reworking of an older, rejected etymology of ᴹQ. Elda (“Departed Elf”) from the root ᴹ√LED “go, fare, travel” (Ety/ELED).