Sør-Audnedal (former name: Søndre Undal or Sør-Undal) is a former municipality in Vest-Agder county in Norway. It is located in the central part of the present-day municipality of Lindesnes.
The municipality of Sør-Audnedal means "southern Audnedal", since it is the southern part of the old Audnedal municipality which encompassed the Audnedalen valley. The name Audnedal (Old Norse: Auðnudalr) is named after the Audna river (Old Norse: Auðna) which runs through the valley ("-dalr") and empties into the Snigsfjorden. The river name means "destruction".
The municipality of Søndre Undal was established in 1845 when the old Undal municipality was divided into Nordre Undal and Søndre Undal. At that time, Søndre Undal had a population of 3,893. The name was later changed to Sør-Audnedal. On 1 January 1899, the western part of Sør-Audnedal, Spangereid, was separated to become a municipality of its own. The split left Sør-Audnedal with 2,958 inhabitants. On 1 January 1964, Sør-Audnedal was merged with Vigmostad and Spangereid to create the new municipality of Lindesnes. Prior to the merger, Sør-Audnedal had a population of 2,323.
Audnedal is a municipality in the county of Vest-Agder, Norway. The new municipality of Audnedal was created on 1 January 1964 after the merger of Grindheim and Konsmo. The municipality's administrative centre is the village of Byremo.
The old municipality (see Undal) had quite different borders: It was established as a municipality on 1 January 1838 (see formannskapsdistrikt) but in 1845 it was divided into Nord-Audnedal (divided in Konsmo and Vigmostad in 1911) and Sør-Audnedal (Spangereid separated in 1899).
It is an inland municipality, and Åseral municipality borders it to the north, Hægebostad to the west, Lyngdal and Lindesnes to the south, and Marnardal to the east. In the north-east it borders Evje og Hornnes in the county of Aust-Agder.
The Old Norse form of the name was Auðnudalr. The first element is the genitive case of the river name Auðna (now Audnedalselva) and the last element is dalr which means "valley" or "dale". The river name is derived from the Norse word auðn which means "destruction" (because of flooding).