A proposed alternate name of Glaurung, but the change was rejected (PE17/183). This name is a combination of ang “iron” and ruin “fiery red”.
Sindarin
Angruin
noun. 'Iron Fire'
angruin
masculine name. Iron Fire
Glaurung
noun. Tolkien notes "Alter Glaurung > Angruin"
prop. n. Tolkien notes "Alter Glaurung > Angruin". FAngruin
prop. n. 'Iron Fire'. Tolkien notes "Alter Glaurung > Angruin".