c.1860, as a place name, originally applied to part of what is now eastern Colorado (Idaho Territory organized 1863; admitted as a state 1890); from Kiowa-Apache (Athabaskan) idaahe "enemy," a name applied by them to the Comanches.
State in the Rocky Mountains bordered by British Columbia, Canada, to the north; Montana and Wyoming to the east; Utah and Nevada to the south; and Oregon and Washington to the west. Its capital and largest city is Boise.