A river in Beleriand (S/123). The meaning of this name is unclear. Given the river’s location in Ossiriand, this name might be Nandorin instead.

Conceptual Development: This river was named Duilwen in Silmarillion drafts from the 1930s (LR/263). In The Etymologies, it was designated an Ilkorin name, a compound of Ilk. duil “river” and a form of Ilk. gwene “green” (Ety/DUI, GWEN). Like many of the river names in Ossiriand, Tolkien did not give a new etymology of the name after he abandoned the Ilkorin language.