What is "dagling"

The Dagling or Dögling dynasty was a legendary clan of the petty kingdom Ringerike in what today is Norway. It was descended from a Dag the Great.

In the Ynglinga saga, Snorri Sturluson writes that the clan was descended from Dag the Great whose daughter Dageid married the Swedish king Alrekr and was the mother of Yngvi and Alf.