The “Great River” of northwestern Middle-earth (LotR/52), a compound of and “long” and duin “river”, and thus literally meaning “Long River” (RC/765, VT48/23).
Conceptual Development: This river was first mentioned as N. Anduin in the earliest versions of the “Fall of Númenor” from the 1930s (LR/33). In the earliest drafts of the Lord of the Rings from the 1940s this river was named N. Beleghir “Great River”, but it was quickly changed to Anduin (RS/410). As he composed the Lord of the Rings, Tolkien considered other variants: Sirvinya “New Sirion” (TI/119) and Andon (TI/298), but all were rejected in favor of Anduin.
topon. -. Q. Anduine.