From Tolkien Gateway

The Dwimorberg or Haunted Mountain was a mountain east of the Firienfeld in Dunharrow[1] in the centre of the White Mountains[2][3].

The Dwimorberg was brooding and black. Its lower slopes were covered with sombre pines, which included the Dimholt,[4] a wood of dark trees[5]. In a hollow place in front of the root of the mountain stood a single mighty standing stone. Beyond in a deep glen in the wall of rock in a deep glen was the Dark Door, which led inside the Dwimorberg to the haunted Paths of the Dead.[6]

The folk of Rohan said that the wraiths of the Oathbreakers haunted the mountain, prevented the living to use the Paths of the Dead and came out like shadows into the Harrowdale at times of great unquiet and coming death.[7]

Etymology[edit | edit source]

The name means "Phantom Mountain" or "Haunted Mountain"[1] in Old English, representing the Rohan language,[8] from dwimor ("phantom", "ghost") and beorg ("mountain").

The first element dwimor is also seen in the names Dwimordene (Lothlórien)[9] and Dwimmerlaik (given to the Witch-king) in the language of Rohan.[10][11]