Hills in north-eastern Mirkwood, translated “Dark Mountains” (UT/280), also known as Emyn-nu-Fuin “Mountains of Mirkwood” (UT/281). This name is a combination of the plural of amon “hill” and the plural of the adjective dûr “dark”.
Sindarin
Emyn Duir
noun. dark mountains
emyn duir
place name. Dark Mountains
emyn (pl. of amon “hill”), duir (pl. of dûr “dark”) David Salo: “dh and mh were liable to revert to d and m when they came to follow a nasal after syncope” TolkLang message 19.31.