A name the Sindarin used for themselves, mostly used in the plural forms Eglath, Eglain or Egladhrim (S/58, MR/170, WJ/365). It was often applied more specifically to the people of Círdan (WJ/380, PM/392 note #35). This name is derived from the adjective eglan “forsaken” < ✶heklanā, whereas the prefixal form Egla- (surviving only in names) was derived from the primitive noun form ✶hek(e)lā “a waif or outcast” (WJ/365).
Conceptual Development: In the Gnomish Lexicon from the 1910s, the word G. Egla was given as the Gnomish name for all Elves, meaning “a being from outside” and related to the word G. edh “outside” (which took the form eg before l) and ᴱQ. Elda (GL/32; LT1A/Eldar, Eglamar). Its class-plural Eglath also appeared in the Gnomish Lexicon (GL/50, entry idhrin). When Tolkien revised the phonology of the Noldorin language, he switched the language of this word to Ilk. Egla “Elf”, equivalent of ᴹQ. Elda and N. Eledh (Ety/ELED).
After Tolkien abandoned the Ilkorin language, he revised the meaning of this name to “The Forsaken”, a name the Sindar gave themselves after they were left in Beleriand (S/58). In this new sense, the class-plural S. Eglath “Forsaken” first appeared in a chart of the divisions of the Elves from the early 1950s, where it was equated to (and possibly replaced) Q. Ecelli of the same meaning (MR/170). The singular form Eglan appeared in his Quendi and Eldar essay from 1959-60, equated to Q. Hekel and with the etymology discussed above (WJ/365).