søn

In a baptism, confirmation or census entry, søn gives a person's place in the family, and the patronymic gives the father's given name. The name moved down one step each generation: Ole's children were Olsen and Olsdatter, and the children of his son Halvor were Halvorsen and Halvorsdatter.

Many emigrants took an English form in America, such as Peterson for Pedersen. A shared patronymic only means the fathers had the same given name, so it is no proof of kinship. The plural is sønner, and sønnesøn is a son's son.