A precursor to S. Nanduhirion “Vale of Dim Streams” appearing in Lord of the Rings drafts from the 1940s (RS/433), apparently ending with the lenited class-plural hiriath of N. sîr “stream”, as suggested by Roman Rausch (EE/1.14).
Noldorin
tum
noun. (deep) valley
tum
noun. deep valley, under or among hills
tum-halad
place name. Tum-halad
tum dincelon
place name. Dimrill-dale
nûr
adjective. deep
imlad
noun. deep valley, narrow valley with steep sides (but a flat habitable bottom)
nanduhiriath
place name. Dimrill-dale
nanduhirion
place name. Dimrill-dale
nûr
adjective. deep
rhaudh
adjective. hollow, cavernous
rosta-
verb. to hollow out, excavate
Earliest name for S. Nanduhirion appearing in Lord of the Rings drafts from the 1940s (RS/432), apparently starting with N. tum “valley” and ending with Ilk. celon “river”, but the meaning of the middle element is unclear. Roman Rausch suggested it might be related to Ilk. dimb- “sad, gloomy” (EE/1.14).