S. #în¹ n. “year”
Conceptual Development: The word în first appeared in The Etymologies from the 1930s with the gloss and derivation given above. It did not directly appear in Tolkien’s later writings, but was an element in several later words such as S. ínias “annals” and S. iphant “aged” (lit. “year full”). Furthermore, its Quenya cognate yén did reappear in the Lord of the Rings appendices.
In The Etymologies, both N. în and ᴹQ. yén were glossed “year”, and there were other words for longer periods of time, such as ᴹQ. qantien “century, (lit.) full year” and N. anrand “cycle, age”. In the Lord of the Rings and other later writings, Tolkien changed the meaning Q. yén to an “Elvish century” of 144 years. It is quite likely that S. în also changed to this meaning, but since it did not appear as an independent word in later writing, we have no direct confirmation of this.
Neo-Sindarin: Most Neo-Sindarin writers continue to use în with the sense “year” (that is, a solar year of 365 days). If you are concerned with this word’s true meaning, you might instead use a neologism for this period of time, such as ᴺS. lóran or ᴺS. coranor, but since these are not in widespread use, it is less likely a reader would understand your meaning.
Reference ✧ MR/200 ✧ ín
N. în n. “year”
References ✧ Ety/YEN
|ᴹ√YEN > în||[jēn] > [jīn] > [īn]||✧ Ety/YEN|
G. fann n. “year”
References ✧ GL/34; LT1A/Fanuin