The mother-name of both of the twins Amrod and Amras, though at Fëanor’s insistence, she gave one of them a new mother-name: Umbarto, which Fëanor changed to the less ominous Ambarto (PM/353-4). The name is a compound of amba “up” and russa “red-haired”, and refers to the red hair of the twins.
Sindarin
amras
masculine name. Top-russet
Twin brother of Amrod and second(?) youngest of the sons of Fëanor (it is unclear which of the twins was born first). The name is a compound of am “up” and ross “red-haired” (PM/353, VT41/10), an adaption of his Quenya nickname Q. Ambarussa. In a few places the name appears as Amros (PM/366, VT41/10), closer to its Sindarin elements.
Conceptual Development: In the earliest Lost Tales, this character was first named G. Dinithel (LT2/251), revised in the Lays of Beleriand to ᴱN. Durithel, then ᴱN. Díriel (LB/86). The name remained N. Díriel in Silmarillion drafts from the 1930s, and the form Diriel (with a short i) appeared in The Etymologies (Ety/DER, GYEL). The name was revised to Amras in Silmarillion revisions from the 1950s-60s (WJ/197).