A variant of the name Dorthonion, apparently the proper Sindarin name of that region. This name is a combination dôr “land”, i “the” and the plural thuin of thôn “pine” (PE17/81).
Conceptual Development: In The Etymologies from the 1930s, a similar variant N. Dor-na-Thuin appeared for Ilk. Dorthonion (Ety/THŌN).
topon.