Definition of: Kootenay

(k′tə·nā)
A river rising in Kootenay National Park in SE British Columbia; 543 square miles; established 1920; flowing through northern Montana and Idaho, thence through Kootenay Lake, a lake 75 miles long in SE British Columbia, to the Columbia River; total length 450 miles, of which 276 are in Canada. Also, in the United States, Koo′te·nai.