A noun for a “cleft”, most notably in Calacirya “Light-cleft” as mentioned in the Namárië poem (RGEO/62; LotR/377).
Conceptual Development: In Silmarillion drafts from the 1930s, this name was ᴹQ. Kalakilya (LR/173; MR/102), and the word ᴹQ. kilya “cleft, pass between hills, gorge” appeared in The Etymologies of the 1930s as a derivative of the root ᴹ√KIL “divide” (Ety/KIL). The word kilya also appeared with the gloss “chasm” in Lament of Atalante from the 1930s and 40s (LR/47, 56; SD/247, 310), but at some point when composing the final versions of the Namárië poem Tolkien switched to Calacirya, and he made the same change in later versions of Silmarillion drafts (MR/102).
Neo-Quenya: I’d avoid this word for Neo-Quenya, as it is too easily confused with cirya “ship”.
ciris _("k")_noun "cleft, crack" (LT2:337 - obsoleted by cirissë?)