A verb for “to quench” appearing only as an element in uluithiad “unquenchable” in Lord of the Rings drafts of the 1940s (SD/62). Patrick Wynne suggested it might be related to Q. luita- “flood, drench” and the root √LUY (VT48/31). The problem with this theory is that there is no obvious reason for the suffix -thia.

Another derivation might be from primitive *luktya-, which seems to be the theory behind Helge Fauskanger’s neologism ᴺQ. luhtya- “extinguish”. Alternately, its derivation might be similar to Exhilic Noldorin leithia- “release” from The Etymologies of the 1930s under the root ᴹ√LEK, whose Quenya cognate ᴹQ. lehta- indicates a primitive form of *lekta-. Leithia- had an (archaic?) infinitive form lheitho, so perhaps there was a phenomenon of “reverse intrusion” (as suggested by Elaran) whereby an i-diphthong might produce an i after a th: leitha- > leithia-. If so, then luithia- might be from LUK + tā. The problem with this theory is that (a) the attested root meanings of √LUK are not particularly suitable for “quench” and (b) there is no clear reason why u did not become o to produce *loethia-.

The above commentary is based on a conversation from the Vinyë Lambengolmor Discord Server (VLDS) in 2023.