Quenya name for a Balrog, a combination of some derivative of the root √BAL “power” with rauco “demon” (SA/rauko, val; PE17/48). It also appeared as Valarauka (PE17/48).
Conceptual Development: In the Qenya Lexicon from the 1910s, their name was either ᴱQ. Valkarauke “✱Cruel Demon” or ᴱQ. Malkarauke “✱Torment Demon” (QL/58, 60, 101-2). In The Etymologies from the 1930s, the second form reappeared as ᴹQ. Malarauko of similar meaning (Ety/RUK), but in this conceptual period it seems to be a loan word from either Noldorin or Orcish (LR/404). The forms Valarauka or Valarauko emerged in Tolkien’s later writing (PE17/48, WJ/415).
Valarauco ("k") noun "Demon of Might" (here vala- assumes its basic meaning "power, might"), Sindarin balrog(WJ:415). Pl. Valaraucar (sic, not -or) "Balrogs", apparently containing rauca (q.v.) as an alternative form of rauco "demon" (SA:val-, SA:rauco). Earlier forms from the "Qenya Lexicon" are Valcaraucë, Malcaraucë (q.v.), apparently abandoned in LotR-style Quenya.