What is the name of the primeval cow in Norse creation myth?

The primeval cow in Norse creation myth is Auðumbla.

Auðumbla appears in the Gylfaginning section of Snorri Sturluson's Prose Edda. In the primordial realm of ice and fire, the cow feeds the frost giant Ymir with milk from four rivers flowing from her teats. She herself survives by licking salty, frosted stones.

Over three days, Auðumbla's licking reveals Búri from the ice: first his hair, then his head, and finally his whole body. Búri becomes the ancestor of Odin, Vili, and Vé, while Ymir becomes the forefather of the jötnar. The cow therefore nourishes both of the major ancestral lines in the myth—the giants through Ymir and the gods through Búri.

Auðumbla's story is recorded only in the Prose Edda, a medieval Icelandic work composed in the 13th century, so details should not be treated as a complete account of pre-Christian Norse belief. The name has variant spellings, including Auðhumla and Auðumla, but these refer to the same mythic cow.