Adurant
From Tolkien Gateway
The river Adurant was the southernmost of the seven rivers of Ossiriand marking its southern boundary.
ran from southern Ered Luin into the river Gelion, marking the southern boundary of Ossiriand.
Etymology
The name means Doublestream (from adu "double" and rant "course") in Sindarin, referring to a parting of the river about the isle of Tol Galen.