Vetrnaetr

Vetrnætr (anglicized as Vetrnaetr; Old Norse for winter nights) was a specific time of year in Viking Age Scandinavia. According to Zoega's Concise Dictionary of Old Icelandic, vetr-nætr referred to "the three days which begin the winter season". The term is attested in the narrative of some of the Fornaldarsögur, mostly to express passage of time ("as autumn turned into winter").

The exact term "winter nights" is not mentioned in the Ynglinga saga by Snorri Sturluson where (in chapter 8) the three great sacrifices of the year are prescribed:

Specific sacrifices held at the beginning of winter during the Old Norse period were álfablót and dísablót.