A noun for “fading” indicated by the month name Narquelië “Sun-fading” in The Lord of the Rings appendices and its drafts (LotR/1110; PM/134). It was likely the gerund (verbal noun) of the verb quel- “to fade”.
Conceptual Development: The Declension of Nouns from the early 1930s had ᴹQ. qelesta “dying, fading” (PE21/8).
histanë pre-classical participle? "fading" (MC:213; this is "Qenya")