(1) Lieutenant of Turgon, guardian of the inner gate of Gondolin, who in the sack of that city slew and was slain by Gothmog, Lord of Balrogs.
Book of Lost Tales 2, appendix:
Both "The Tale of Gondolin" and the "Nauglafring" derive this name from ecthel 'fountain', to which corresponds Quenya ektelë ."
The later, official, Quenya form is ehtelë , which corresponds with Sind. eithel.
Legitimate alternates would be:
Ektello (ancient Quenya: of the fountain)
Ehtello (Quenya: of the fountain)
Eithelo (Sind.: of the fountain)
But then there is the possibility that Christopher misinterpreted his fathers work (ok, little chance here :) ), because we also have:
Aegthelion (comp. Cu-thalion, Hurin Thalion, Aeg-nor):
Sharp one who does not stray from his purpose!
(cf. Didier Willis' Sindarin wordlist).
However, using "Lost Road" under "Etymologies":
From what I understand one could interprete ech (spear) -thelion (that does not stray).
From the fact that ecthel in the meaning of point-of-spear never appears anywhere but in the "Etymologies" (which were largely abandoned
by JRRT later on), one could conclude that he left that Road. Furthermore, ecthel would IMHO always be a SINDARIN word, the whole
sound and spelling is not Quenya.
But it's an alternative interpretation all the same, and I always say: "when it's there it's there":).
Another proof that Ardology is still an incomplete science, and Christopher does not always have a concluding word on everything, and
that much research has yet to be done! (Which makes us happy:)
What I found was this in the Etymologies and I quote in a short version:
ehtar = spearman.
êg = thorn. cf.Egthelion, ecthelion
[STELEG] ech = spear.
When I looked under STELEG I read : point of spear. with an sf. to ecthelion.
I do believe Ecthelion means something like point of the spear / spearhead / front of the spear and actual meaning; man/elf in front / commander of the assault.
There might be other solutions like Ech -Elion - Spear(man) of the star / Spear(man) of the sky /
Spearhead of star/sky as EL can mean both star and sky.
I wouldn't call Ecthelion a Sindarin-name, the Sindar were greyelves, a sub-clan of the Umanjar-Elves of the Teleri line (the Moriquendi / Darkelves) of those who originally came to Beleriand but never reached Valinor. I would rather call it a Noldorin-name or Eldar-name (Kalaquendi / Lightelves). Gondolin was mainly inhabited by Noldor-Elves though it can't be ruled out that many Sindar / Teleri had found refugee there.
I guess you can use Steleg as an alternative name
References: Book of Lost Tales 2 Lost Road
See also Elatan/Amillo-(Valar)'s article in his Annals of Arda, choose "E" for elves having names starting with E, then choose "Ecthelion" from the list appearing on the right.