A word for “mist” appearing as an element in several names. It is not directly attested in Tolkien’s later writings, but ᴹQ. híse “mist, fog” appeared in The Etymologies of the 1930s derived from primitive ᴹ✶khīthi, indicating a stem form of hísi- [†híþi-] (Ety/KHIS). Its continued appearance in words like Q. Hísilómë “Land of Mist” (S/118) and Q. hísilanya “mist thread” (PE17/60) indicates its ongoing validity.
Conceptual Development: ᴱQ. hīse appeared in the Qenya Lexicon of the 1910s as a derivative of the early root ᴱ√HISI alongside a variant ᴱQ. histe, but there it was glossed “dusk” (QL/40). In drafts of the Oilima Markirya written circa 1930 it was glossed “haze” (PE16/62) or “mist” (PE16/75; MC/221), but in the final 1931 iteration of the poem it appeared only in the very-loosely translated phrase ᴱQ. úri nienaite híse “a bleared sun”, perhaps literally “✱sun [with a] tearful mist” (MC/214). In the Declension of Nouns from the early 1930s it was “mist” (PE21/32) and in The Etymologies of the late 1930s “mist, fog” as noted above, so Tolkien seems to have stuck with the meaning “mist” thereafter.
hísë (þ) (stem #hísi- because of the primitive form ¤khīthi, cf. hísilanya, Hísilómë) (1) noun "mist, fog" (KHIS/KHITH). According to VT45:22, hísë is also the name of Tengwa #11 in the pre-classical Tengwar system presupposed in the Etymologies, but Tolkien would later call #11 harma/aha instead.