A noun in The Etymologies of the 1930s glossed “cave”, apparently a combination of N. gath “cavern” and ᴹ√ROT “tunnel” (Ety/GAT(H)). Its initial element also appeared in the name N. Doriath “Land of the Cave”, but in later writings S. Doriath was redefined as “Land of the Fence” with final element S. iath “fence” (WJ/370), so N. gathrod “cave” was probably abandoned.
Noldorin
rhû
noun. loud sound, trumpet-sound
rhû
noun. loud-sound, trumpet-sound
rhûn
noun. east, eastern; †rising
rhûn
noun. east
rhûnaer
place name. Eastern Sea
rhufen
adjective. east
rhufen
noun. east
amrûn
noun. east, orient
fela
noun. cave
fela
noun. cave
gathrod
noun. cave
gathrod
noun. cave
nella-
verb. to sound (of bells)
rhomru
noun. sound of horns
rhond
noun. cave roof
rhond
noun. vaulted or arched roof, as seen from below (and usually not visible from outside), or a (large) hall of chamber so roofed
rhonn
noun. cave roof
rhonn
noun. vaulted or arched roof, as seen from below (and usually not visible from outside), or a (large) hall of chamber so roofed
rond
noun. cave
tham
noun. hall
tham
noun. hall
thamas
noun. great hall
thamb
noun. hall
thambas
noun. great hall
An archaic noun appearing as N. †rhû “loud sound, trumpet-sound” in The Etymologies of the 1930s, derived from ON. rūma under the root ᴹ√ROM “loud noise, horn-blast” (Ety/ROM), where the ancient m became v and vanished after u. After these sound changes it seems this word was no longer distinct enough, and in modern speech was replaced by rhomru “sound of horns”.
Neo-Sindarin: Since the unvoicing of initial liquids did not occur in Sindarin, many people adapt this word as (still archaic) ᴺS. †rû for purposes of Neo-Sindarin, as suggested in HSD (HSD).