See Nogrod. 104

Tumunzahar is the Dwarvish name for Nogrod, the citadel of the Dwarves that lay in the central part of the Blue Mountains, near Mount Dolmed.

Tumunzahar is apparently Khuzdul for "Hollowbold". Magnus Åberg has suggested that the name consists of the unattested elements tûm ("bold/delving"?) and zahar ("hollow"?).