The egla- element of this name is translated by Tolkien as simply 'Elven', but in fact it seems to refer more specifically to the Sindar (whose old name for themselves was Eglath, the Forsaken People). Taken together with the fact that the entire name Egladil is Sindarin rather than Silvan, this implies that the name was given to this region by the Sindarin lords who ruled Lórien before the coming of Galadriel and Celeborn.