yassë (2) adv. "once upon a time" (YA); writers may rather use yalúmessë or yáressë of similar meaning to avoid confusion with # 1 above.
Quenya
yassë
in which
yassë
once upon a time
yassë
conjunction. where [relative], in which place
yáressë
once upon a time
yáressë noun in locative "once upon a time" (locative form of yárë) (YA)
ya
pronoun. which, that (relative pronoun)
The basic relative pronoun in Quenya, mostly used in inflected forms such as: yassen tintilar i eleni “wherein the stars tremble” (LotR/377). See the entry on relative pronouns for further discusion.
Conceptual Development: The use of ᴱQ. ya as a relative pronoun dates back to the Early Qenya Grammar (EQG) of the 1920s (PE14/54), but for a period in the 1930s and 40s ᴹQ. ya was used more as a remote demonstrative (Ety/YA; PE23/96-98). See the entry on correlatives for more on this usage as of 1948.
yalúmessë
once upon a time
yalúmessë noun in locative "once upon a time" (locative form of yalúmë) (YA)
#yassë (1) relative pronoun in locative "in which", pl. yassen referring back to a plural noun (relative pronoun ya + locative ending) (Nam, RGEO:66)