Apparently a feminine suffix attested in the name Thuringwethil “(Woman of) Secret Shadow” (Ety/THUR) and the noun tóril “queen” (Ety/TĀ).
Doriathrin
cwend
noun. Elf
* -il
suffix. feminine suffix
Beware, older languages below! The languages below were invented during Tolkien's earlier period and should be used with caution. Remember to never, ever mix words from different languages!
A Doriathrin noun meaning “Elf” derived from primitive ᴹ✶kwenedē (EtyAC/KWEN(ED)), an example of the Ilkorin syncope.
Conceptual Development: This word is nearly identical to earlier Gnomish Cwenn “Elf” before Tolkien revised the phonological history of the Noldorin language so that [kw] became [p].