A widely used feminine suffix in Sindarin (PE17/23, 190). It sometimes more specifically meant “-daughter” in names such as Elrenniel “Arwen; ✱(lit.) Elrond-daughter” (PE17/56) or Tinúviel “Daughter of Twilight” (S/165), but in other cases it simply meant female as in names like Gilthoniel “Star-kindler [female]” (PE17/23). It was also sometimes reduced to -il or -el. See the entry on the root √YE(L) for a discussion of various conceptual vacillations in its connection to “daughter”.
Conceptual Development: The use of N. -iel dates back to Noldorin, where its connection to “daughter” was more explicit, though Tolkien vacillated on whether the suffix was based on ᴹ√YEL or ᴹ√SEL (Ety/SEL, YEL). The suffix does not appear to be specifically feminine in Gnomish of the 1910s, however, appearing in both female names like G. Níniel (LT2/100) and male names like G. Inwithiel (LT1/22).
_2nd sg./pl. poss. suff. _your. Maybe the polite form of this suff. See also the paradigm of poss. suff. in PE17:46. Later -lein. >> -eg, -lein