Dagorlad's name in Sindarin is in reference to the major battle between the army of the Last Alliance and the hordes of Mordor at the end of the Second Age. The area of this battle, full of death and rotting corpses, is now known as the Dead Marshes. Although the bodies of the dead are long gone, their ghastly shapes can still be seen floating ethereally beneath the surface of the blackish waters of the swamp known as the Dead Marshes.
In Peter Jackson's movie adaptation of the Lord of the Rings film trilogy, Dagorlad is misspelled as Dagorland on various maps shown in the films, and in the appendices of the special extended DVD editions.
Places of Middle-earth and Arda
Forests & Mountains:
The rest of Arda: