An untranslated word appearing in notes on The Feanorian Alphabet from the late 1940s or early 1950s (PE23/26). It might be a later iteration of G. adhwen “approach, avenue” from the 1910s, or is perhaps related to S. adu and ᴹQ. atwa “double”.
Noldorin
ist
noun. lore, knowledge, lore, knowledge; [G.] feeling, sensation; notion
ist
noun. lore, knowledge
istui
adjective. learned
ista-
verb. to have knowledge, to have knowledge, [G.] know, be aware, perceive, feel
ista-
verb. to have knowledge
istui
adjective. learned
iaeth
noun. neck
ianw
noun. bridge
adwen
noun. [unglossed]
angol
noun. deep lore, magic
borth
?. [unglossed]
clei
?. [unglossed]
coen
?. [unglossed]
curunir
noun. man of craft, wizard
diragas
?. [unglossed]
goll
adjective. wise
goll
adjective. wise
golw
noun. lore
golwen
adjective. wise, learned in deep arts
iaeth
noun. neck
iant
noun. bridge
ithil
noun. Moon
mauth
?. [unglossed]
menwed
?. [unglossed]
nith
?. [unglossed]
nithrad
?. [unglossed]
noen
adjective. wise, sensible
níth
?. [unglossed]
porennin
?. [unglossed]
rhân
noun. Moon
sail
adjective. wise
telwen
?. [unglossed]
A word for “neck” in The Etymologies of the 1930s derived from primitive ᴹ✶yakta- under the root ᴹ√YAK (Ety/KEM), where the primitive k spirantalized and vocalized to i and the resulting diphthong ai became ae, sound changes that remain plausible in Sindarin as well.
Conceptual Development: There was a similar word G. gath “neck” in the Gnomish Lexicon of the 1910s from primitive ᴱ✶yatt- (GL/36), with the Gnomish sound change of initial y to g.
Neo-Sindarin: For purposes of Neo-Sindarin, I would use iaeth for “neck” as a joining between the head and torso, as opposed to lang as a passage from the mouth to stomach and lungs [including the “✱throat”] and S. ach referring the vertebrae in the neck [“✱(upper) spine”].