From Tolkien Gateway

The river Adorn was one of the rivers which arose in the White Mountains flowing northwest, and joined with the Isen about 150 miles west of the Gap of Rohan at the borders of Enedwaith.[1]

Together with the river Angren the Adorn formed the western border of the Kingdom of Rohan.[2] The triangle of land between the Isen, Adorn, and the White Mountains was nominally part of the Kingdom of Rohan,[3] but in the late Third Age it was a contested area between the Rohirrim and the Dunlendings. Lord Freca held lands at either side of the river around T.A. 2758.[4]


The name Adorn is said to be a of pre-Númenórean origin,[5] adapted in form to suit the Sindarin language.[6]