Amras' father-name in Quenya was Telufinwë, "Last [of] Finwë", for he was the last of the sons of the House of Finwë and its short form was Telvo. His mother-name was originally Ambarussa ("Top-russet", referring to his hair), the same as his twin Amrod, but Fëanor insisted that the twins ought to have different names and Nerdanel prophetically called him Umbarto, "The Fated" (from umbar = "fate"). His father, disturbed by it, changed it to Ambarto, "Upwards-exalted" (from amba = "upwards, top" and arta = "exalted", "lofty"). Nevertheless both twins called each other Ambarussa.
The name Amras is the Sindarin version of Ambarussa.
In later notes found in The Peoples of Middle-earth, Tolkien mentions that he wished to change the name to Amros because of linguistic issues. While this occured late in life, and there are no known manuscripts written later that contradict this, its canonicity is in dispute.
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).