Wordorigins.org

The name Saskatchewan originally applied to the river of that name. It is from the Cree name for the river, kisiskatchewan, meaning swift current. The name begins appearing in documents about the fur trade in 1754. The current spelling was formalized in 1813 by geographer David Thompson.

The Saskatchewan district of the Northwest Territories, the nucleus of what would become the province, was formed in 1882. The present boundaries were established in 1905 when it became a province.

(Sources: Dictionary of Canadian Place Names; Illustrated Dictionary of Place Names)