Arendal is a city and municipality in the county of Agder, Norway. It is the administrative center of Aust-Agder county, and belongs to the geographical region of Sørlandet. The municipality is bordered in the southwest by Grimstad, in the northwest by Froland, and in the northeast by Tvedestrand municipalities.
The Norse form of the name was probably "Arnardalr". The first element is then the genitive case of "orn" m 'eagle', the last element is "dalr" m 'valley, dale'.