Úmaiar (or Umaiar) is a Quenya word referring to the evil spirits corrupted by Morgoth. The chief among them were the Balrogs.
 See also
- ↑ 1.0 1.1 J.R.R. Tolkien, Christopher Tolkien (ed.), Morgoth's Ring, pp. 79 (commentary to §30), 165 (commentary to §18)