Porsgrunn

Etymology
, first part, either from , from , if not from. Last part from  and, from , from , from Pre-Germanic , from.

The name of the city was first mentioned as Porsgrund by the writer Peder Claussøn Friis in his work Concerning the Kingdom of Norway, in 1576, this spelling was in use until 1931 when it was changed to Porsgrunn.

The name was probably given during medieval times to the then swampy area by the nuns of Gimsøy Abbey, who went here to collect the shrub.