An earlier name for S. Nenning, the river flowing past the haven of Eglorest, marked Ilkorin and translated “Elf-river” in The Etymologies (Ety/ELED). It is likely an elaboration of Ilk. Egla “Elf”. Earlier still the river was named Eldor (SM/227), perhaps containing the earlier (rejected) Ilkorin word Ilk. Eld “Elf”.
Doriathrin
esgal
noun. screen, hiding, roof of leaves
esgalduin
place name. River under Veil
eglor
place name. Elf-river
A noun meaning “screen, hiding, roof of leaves” derived from the root ᴹ√SKAL (Ety/SKAL¹). Apparently the initial [sk-] became syllabic [ṣk-], which then became [esk-]. Afterwards the [[ilk|[esk] became [esg]]].