In Norse mythology, how many legs did Odin's horse Sleipnir have?

In Norse mythology, 'Sleipnir' (Old Norse 'slippy' or 'the slipper') is an eight-legged horse ridden by Odin a widely revered god in that mythology. 'Sleipnir' is attested in the 'Poetic Edda', compiled in the 13th century from earlier traditional sources, and the 'Prose Edda', written in the 13th century by Snorri Sturluson. In both sources, 'Sleipnir' is Odin's steed, is the child of Loki and Svaðilfari, is described as the best of all horses, and is sometimes ridden to the location of Hel. The 'Prose Edda' contains extended information regarding the circumstances of 'Sleipnir's' birth, and details that he is grey in color.

Odin appears as a prominent god throughout the recorded history of Northern Europe, from the Roman occupation of regions of Germania (from c. 2 BCE) through movement of peoples during the Migration Period (4th to 6th centuries CE) and the Viking Age (8th to 11th centuries CE). In the modern period the rural folklore of Germanic Europe continued to acknowledge Odin. References to him appear in place names throughout regions historically inhabited by the ancient Germanic peoples, and the day of the week Wednesday bears his name in many Germanic languages, including in English.