Quenya 

yén

long year

yén noun, Elvish "long year" of 144 solar years, 52,596 days (Nam, Appendix D, E; RGEO:66. Tolkien earlier defined yén_ as 100 solar years; see PM:126. In the Etymologies, stem YEN, it seems to mean simply "year", but in the LotR Appendices the word for "year" instead appears as _loa or coranar, q.v.) Yénonótië "reckoning of years" (MR:51). Pl. yéni in Nam and Etym, entry YEN though the plural form is misread as "yen-" in the printed version of the Etymologies, cf. VT46:23. Yéni pa yéni "years upon years" (VT44:36). Pl. genitive yénion in yénion yéni "ages of ages" (VT44:36)