Several mountains in the area have the ending -ronden (Digerronden, Høgronden, Midtronden, Storronden and Vinjeronden), and this is the finite singular of the same word. The word rond was probably originally the name of the long and narrow lake such as Rondvatnet and the mountains surrounding the lake were then named after this lake.
In the region, several peaks have names ending in -ronden (Digerronden, Høgronden, Midtronden, Storronden, and Vinjeronden), which is the singular form of a word. It's likely that the term rond initially referred to a lake like Rondvatnet, with surrounding mountains then being named after this body of water.