From Kook Science

Ontario, from the Huron Ontarí:io ("great lake") or Iroquoian Skanadario ("beautiful water", "sparkling water"), so-named since Confederation, having previously been known as Upper Canada, then Canada West, covering a territorial expanse having been carved from the Province of Quebec following settlement by United Empire Loyalists who had been expelled from the newly-formed United States of America with the later addition of large swaths of Rupert's Land.