Stated to be an alteration of sell , remodelled after ion "son" (OS *jondo). It was "a change assisted by the loss of s in compounds and patronymics", hence the ending -iel in several feminine words
Noldorin
el
noun. star
ell
noun. sky
elf
noun. friend
elw
adjective. (pale) blue
elw
adjective. (pale) blue
iell
noun. daughter
iell
noun. girl, maid
iell
noun. daughter
mellon
noun. friend
gael
adjective. pale, glimmering
meldir
noun. friend
meldis
noun. friend
mellon
noun. friend
sell
noun. daughter
sell
noun. girl, maid (child)
ingem
adjective. old (of person, in mortal sense: decripit, suffering from old age)
New word coined by the Elves after meeting with Men
o
preposition. from, of (preposition (as a proclitic) used in either direction, from or to the point of view of the speaker)
According to WJ/366, the preposition "is normally o in all positions, though od appears occasionally before vowels, especially before o-". With a suffixed article, see also uin
lhûn
adjective. blue
a
conjunction. and
ar
conjunction. and
geil
noun. star
glinn
noun. (pale) blue
gwind
noun. pale blue
min
cardinal. one
thond
noun. friend
alag
adjective. rushing, impetuous
aran
noun. king (used of a lord or king of a specified region)
athan
preposition. beyond
brûn
adjective. old, that has long endured, or been established, or in use
dúath
noun. darkness, shadow
dúath
noun. nightshade
dúwath
noun. darkness, shadow
dúwath
noun. nightshade
eilian
noun. rainbow
eilianw
noun. rainbow
geil
noun. star, bright spark
giliath
noun. all the host of stars
hûn
noun. heart (physical)
lhûn
adjective. (unknown meaning)
This word, which also appears on the map of Middle-earth in LotR, is glossed as "blue" in The Etymologies, but Tolkien later rejected this meaning (as luin was already used in that sense). He then proposed several explanations for it, including the possible adaptation of a Dwarvish name into Sindarin, but he apparently never reached a definitive solution.
maidh
adjective. pale, fallow, fawn
meidh
adjective. pale, fallow, fawn
min
fraction. one (first of a series)
môr
noun. darkness, dark, night
nim-
adjective. pale, white
nimp
adjective. pale, white
taur
noun. king (only used of the legitimate kings of whole tribes)
In LotR/IV:IV, Frodo is called Daur, which might be the mutated form of this word
âr
noun. king (used of a lord or king of a specified region)
âr
noun. king
An element meaning “sky” in several names from The Etymologies of the 1930s: N. Elfaron “Sky-hunter” (Ety/SPAR) and N. Elthoron “Eagle of the Sky” (Ety/THOR). It was derived from the root ᴹ√ƷEL “sky” which had an Old Noldorin form: ON. elle (Ety/ƷEL). However, Tolkien said “In Noldorin and Telerin this is confused with EL star”, implying that the word was not used in modern language; an earlier but rejected version of this entry had archaic N. †ell, el “sky” (EtyAC/ƷEL).
Neo-Sindarin: Despite the above statements, ell is probably the best attested option for “sky” in Neo-Sindarin, and I would use it as such, since it is in fact distinct from S. êl “star”, a word that is itself archaic/poetic versus more common S. gil.