A word in the Gnomish Lexicon of the 1910s appearing as G. lumbri “foul weather”, an abstract elaboration of G. lum “[dark] cloud” (GL/55), based on the early root ᴱ√LUVU or ᴱ√LUB (LT1A/Luvier; QL/57; PME/57).
Neo-Sindarin: If adapting this word to Neo-Sindarin, I would revise it ᴺS. lummor, based on (hypothetical) primitive ✱lu(m)brĭ > lummṛ(e) > lummor, where ✱lu(m)brĭ is a strengthened variant of (hypothetical) primitive ✱lubrĭ that is my proposed basis for ᴺQ. lúrë “bad weather”. I think these derivations could remain valid since the root √LUB “shadow, darkness” survives in Tolkien’s later writings (PE17/168).
Name of the “third dwelling of Melko” in notes associated with the earliest Lost Tales (LT2/279). It was glossed “Gloomy End” in the Gnomish Lexicon (GL/55), a combination of lum “cloud” and fod “end”.