Sif, Old Norse for "kinswoman, Gesippin", is the wife of the thunder god Thor in Norse mythology. With him she has a daughter named Thrud ("strength"). She also has a son, the swift archer Ullr.
When Loki deceitfully cut off her beautiful golden hair, Thor forced him to have a new hair ornament of gold made for her by artful dwarves, the sons of Ivaldi, which could grow like hair.
In older research, the golden hair was interpreted as a symbol of the ripe field of ears, whose golden ornament is cut off in the glow of late summer, but then rewoven by invisible earth forces. But Sif seems to have had no other function in Norse mythology than to be the wife of Thor, as her name also suggests.