One of the havens of Falas along with Brithombar (S/58). This name is apparently a combination of the prefixal form Egla- of Eglan “Forsaken (Elf)” and rest “a cut”, derived from ancient ✶(h)ekla-rista (WJ/365).
Conceptual Development: In Silmarillion drafts from the 1930s, this river was first named Eldorest after the river Eldor, revised to Ilk. Eglorest when the river name changed to Ilk. Eglor (SM/227, 310 note #8). In The Etymologies, this name was designated Ilkorin, related to Ilk. Egla “Elf” and rest “a cut” (Ety/ELED, RIS²). After Tolkien abandoned the Ilkorin language, the meaning of the initial element revised in his “Quendi and Eldar” essay from 1959-60, as given above (WJ/379). In this late essay, Tolkien did not explain the meaning of the second element, but it was clearly from the same primitive form as earlier Ilk. rest and may have retained the same meaning.