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
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”.