Hollowbold

According to the Grey Annals (in volume XI of The History of Middle-earth, the Dwarves first appeared in the Blue Mountains about 2,400 years before the Noldor returned to Middle-earth. This would place the founding of the Hollowbold during the second age of the Captivity of Melkor, a period in which Beleriand was still enjoying peaceful times under starlit skies, long before the making of the Sun.

Based on comments in volume XII of The History of Middle-earth, the Hollowbold was apparently occupied by either the Firebeard or the Broadbeam clan of Dwarves. Based on word order, the Hollowbold seems to have been established by the Firebeards, but this is not stated explicitly.

Hollow here relates to the fact that the city was a cavernous underground dwelling. The closing -bold comes from an Anglo-Saxon word for 'dwelling place', related to modern 'build' (and also to the -bottle in the village names of Hardbottle and Nobottle in the Shire).

Mannish 'Hollowbold' was a direct translation of the Dwarvish name Tumunzahar, but it is not directly equivalent to the Elvish form Nogrod, which means 'Dwarf-dwelling'. In fact Tolkien experimented with various sources for the Elvish name, among which was Novrod (which actually does translate as 'Hollowbold') before settling on the final form. According to notes in volume XI of The History of Middle-earth, this change mirrored the history of the name among the Elves, whereby they originally knew this stronghold as Novrod (translating the Dwarves' own name directly), but the dialect word Nov- for 'hollow' gradually evolved into the more common and familiar Nog- for 'Dwarf'.