Son of the traitorous Easterling chief Ulfang (S/157). This name seems to be Sindarin, and therefore was probably not his true name. It seems to be a combination of [N.] ul- “✱ugly” and [N.] fast “shaggy hair”.
Conceptual Development: This character was named N. Ulfast in Silmarillion drafts from the 1930s (SM/300, LR/287) and appeared in The Etymologies as a combination of ᴹ√ULUG and N. fast, the source of the derivation given above (Ety/ÚLUG, PHAS).
ul (stem “hideous, horrible”) + #fast (“shaggy hair”)