Until 1930 the name was written Avfjellet on maps. The first element is av 'off', the last element is fjell n 'mountain'. The meaning is 'the mountain broken off a larger mountain' (the top of Hafjell lies beneath the larger and taller mountain Nevelfjell, and it could be considered to be a part of this). The first element was pronounced just as [a:], and the h was later added (see h-adding) to emphasize it.