The form helta- in the Etymologies is a misreading according to VT/46:14
Noldorin
an-
prefix. with, by
ann
adjective. long
-ian(d)
suffix. -land
brethil
noun. beech
ada
noun. father, daddy
adar
noun. father
adar
noun. father
anann
adverb. long
anc
noun. jaw, row of teeth
ann
adjective. long
ant
noun. gift
ant
noun. gift
brethel
noun. beech, beech-tree, silver birch
brethel
noun. beech
caer
cardinal. ten
caer
cardinal. ten
calad
gerund noun. light
calad
noun. light
carach
noun. jaws
cûl
noun. flame
dae
noun. shadow
dae
adverb. very
daew
noun. shadow
edhel
noun. Elf
edra-
verb. to open
edro
verb. open!
el
noun. star
fêr
noun. beech-tree
gail
noun. bright light
gal-
prefix. light
galad
noun. light
geil
noun. star, bright spark
geil
noun. star
giliath
noun. all the host of stars
glaur
noun. golden light (of the golden tree Laurelin)
glor-
noun. golden light (of the golden tree Laurelin)
golodh
noun. "Deep Elf" or "Gnome", one of the Wise Folk
golodhrim
noun. Deep Elves, Gnomes
gwath
noun. shade, shadow, dim light
gwath
noun. stain
gwath
noun. shade
ha
pronoun. it
ha
pronoun. it
hana
pronoun. it
hana
pronoun. it
heltha-
verb. to strip
ind
noun. inner thought, meaning, heart
inn
noun. inner thought, meaning, heart
lalf
noun. elm-tree
lalven
noun. elm-tree
lhach
noun. (leaping) flame
lhaden
adjective. open, cleared
lhalorn
noun. elm-tree
lhalwen
noun. elm-tree
lhaw
noun. ears (referring to one person's pair of ears only)
lhewig
noun. ear
lhewig
noun. ear
lhum
noun. shade
lhum
noun. shade
A word appearing as N. lhum “shade” in The Etymologies of the 1930s, derived from the root ᴹ√LUM, most notably an element in the name N. Hithlum (Ety/LUM). It was the cognate of ᴹQ. lumbe, and thus derived from primitive ✱lumbē, which explains why the final m survived as a reduction of mb.
Conceptual Development: The earliest iteration of this word was G. lôm {“pool, sl...” >>} “gloom, shade” from the Gnomish Lexicon of the 1910s, based on primitive ᴱ✶lou̯me (GL/54) and probably derived from the early root ᴱ√LOMO as suggested by Christopher Tolkien (LT1A/Hisilómë). In this early document, G. lum or glum was “a cloud” (GL/55), likely a derivative of ᴱ√LUVU for “✱dark weather” as also suggested by Christopher Tolkien (LT1A/Luvier). In Noldorin Word-lists of the 1920s Tolkien had ᴱN. {lom >>} lhom “shadow” (PE13/149). This became N. lhum “shade” in The Etymologies, as noted above.
Neo-Sindarin: In later writings, Hithlum was designated North Sindarin and its final element was based on a loan from Q. lómë “dusk”, with the m surviving only because it was from the North dialect (PE17/133; WJ/400). However, the root √LUM “shadow, darkness” also survived in later writings (PE17/168), so I think N. lhum “shade” can be salvaged, though if adapted to Neo-Sindarin it would need to become ᴺS. lum as suggested in HSD (HSD). Given the later use of Q. lumbo for “(dark) cloud”, I think the Gnomish sense G. lum “[dark] cloud” can be salvaged as well.
mell
adjective. dear
mell
adjective. dear
muin
adjective. dear
muin
adjective. dear
na
preposition. with, by (also used as a genitive sign)
na
preposition. to, towards, at
naew
noun. jaw
naew
noun. jaw
A noun for “jaw” in The Etymologies of the 1930s derived from primitive ᴹ✶nakma (✱“bite-thing”) under the root ᴹ√NAK “bite” (NAK). This word remains phonologically plausible in Sindarin, with ancient k vocalizing to i and the resulting diphthong ai become ae, after which the m became v > w; see VT42/26 for a description of the basic phonetic changes. However, naew might have been displaced conceptually by anc “jaw”, which appeared in a number of later Sindarin names and whose Quenya cognate Q. anca appeared in The Lord of the Rings Appendix E.
naur
noun. flame
naur
noun. fire
naur
noun. flame
nauth
noun. thought
nauth
noun. thought
panna-
verb. to open, to enlarge
taen
adjective. long (and thin)
toll
noun. island, (steep) isle rising with sheer sides from the sea or from a river
ui
adverb. ever
A word for “flame” in The Etymologies of the 1930s under the root ᴹ√KUL “golden-red”, but this word was deleted (EtyAC/KUL).