topon. Great River, (lit.) Long River
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. Great River
The Great River of Beleriand (S/120), a combination of sîr “river” and the adjective iaun¹ “wide”, reduced to its suffixal form -ion² also seen in the names of lands (PE17/42).
Conceptual Development: This river was named G. Sirion in the earliest Lost Tales (LT1/238) and was explained as an archaic word for “river” in the Gnomish Lexicon (GL/67). The name N. Sirion appeared in the Etymologies from the 1930s as an elaboration of N. sîr (Ety/SIR). The derivation given above appeared in Tolkien’s “Words, Phrases and Passages from The Lord of the Rings” from the 1950s-60s (PE17/42).
sirion (i hirion, o sirion), pl. siryn (i siryn).