Tjugondag jul ("Twentieth Day Yule"), or Tjugondag Knut ("Twentieth Day Knut"), or Knutomasso, or Nuutinpäivä ("Knut's Day"), in English Saint Knut's Day, is a traditional festival celebrated in Sweden and Finland on 13January. It is not celebrated on this date in Denmark (the Knut day was moved in Sweden, not in Denmark) despite being named for the Danish prince Canute Lavard, and later also associated with his uncle, Canute the Saint, the patron saint of Denmark.Christmas trees are taken down on Tjugondag jul, and the candies and cookies that decorated the tree are eaten. In Sweden, the feast held during this event is called a Knut's party (Julgransplundring, literally "Christmas tree plundering").
Canute Lavard (Knut Levard in Swedish) was a Danish duke who was assassinated by his cousin and rival Magnus Nilsson on 7January 1131 so he could usurp the Danish throne. In the aftermath of his death there was a civil war, which led to Knut being later declared a saint, and 7January became Knut's Day, a name day.
As his name day roughly coincided with Epiphany (the "thirteenth day of Christmas"), Knut's Day and Epiphany were conflated to some degree. In 1680, Knut's Day was moved to 13 January and became known as tjugondag Knut or tjugondedag jul (the "twentieth day of Knut/Christmas").