A noun for “torrent” in The Etymologies of the 1930s based on the root ᴹ√THOR “come swooping down” (Ety/THOR; EtyAC/THOR). In The Etymologies as published in The Lost Road Christopher Tolkien gave the form as thórod (LR/393), but Carl Hostetter and Patrick Wynne corrected this to thôrod in their Addenda and Corrigenda to the Etymologies (VT46/19). However, in normal Sindarin/Noldorin orthography ô is only used for monosyllables, so thórod is the expected form.
Noldorin
narog
place name. Narog
narogardh
place name. realm of Narog
nargothrond
place name. fortress of Narog
old
noun. torrent, mountain-stream
oll
noun. torrent, mountain-stream
thórod
noun. torrent
thórod
noun. torrent
Apparently an alternate name for Nargothrond appearing in The Etymologies from the 1930s (Ety/NÁRAK), a combination of the river name Narog and ardh “realm”.