A word appearing in notes from the mid-to-late 1960s as an element of two different Quenya equivalents of S. Barad-dûr “Dark Tower”: Q. {Lúnaturma >>} Lúnaturco and Taras Lúna. Tolkien states that taras is “tower”, while turco is derived from √TURUK and is thus probably “*stronghold”, so that the word lúna must mean “*dark”. David Salo suggested in a post to the Elfling mailing list in 2012 (Elfling/362.96) that perhaps it was related to lúmë “darkness” from the Markirya poem, both derived from an (unattested) root *√DU “dark”.

Conceptual Development: A similar form ᴹQ. lóna “dark” appeared in The Etymologies of the 1930s as a derivative of the root ᴹ√DOƷ “night” (Ety/DOƷ).

Neo-Quenya: Since ᴹQ. lóna has several other attested meanings (ᴹQ. lóna “island”, Q. lóna “deep pool, well”), I recommend using the later and less ambiguous word lúna for “dark” in Neo-Quenya writings.