Sindarin name of the Entwash (UT/318), also appearing as Onodiōl in Tolkien’s “Unfinished Index” of The Lord of the Rings (RC/334). This name appears to be a combination of Onod “Ent” and l(h)ô “flood”.
Conceptual Development: In Lord of the Rings drafts from the 1940s, this name first appeared as N. Ogodrûth (TI/250), apparently using an earlier name Ogod for “Ent”, as suggested by Roman Rausch (EE/2.35).
onod (“ent”) + lô (“shallow lake, fenland”)