Earlier name for S. Rauros in Lord of the Rings drafts from the 1940s (TI/285), also appearing as Dant-ruin (TI/283). Its first element seems to be dant “✱fall”, as suggested by Roman Rausch (EE/2.39), but the meaning of the second element is unclear.
Noldorin
dant-
verb. to fall
dant-
verb. to fall
dant-ruinel
place name. Dant-ruinel
Written dant- in the Etymologies