The municipality (originally the parish) is named after the Audnedalen valley (), but over time the name was shorted due to a corruption of the language. The first element is the genitive case of the river name Auðna (now Audna). The river name is derived from the word  which means "destruction" or "wasteland" (because of the flooding that often happens along the river).
The municipality is named after the Audnedalen valley (), which was later shortened due to language errors. The river name Auðna (now Audna) is derived from the term meaning "wasteland" or "destruction," referring to the area's frequent flooding.