GREAT SLAVE LAKE (Fr. Lac de l'Esclave), a large irregular sheet of water in a district of the same name in the northwest territories of Canada, between lat. 60° 40' and 63° N., and lon. 109° 30' and 117° 30' W.; length from E. to W., 300 m.; greatest breadth, 50 m. Its N. shores are steep and rough, and from them it receives the outlets of Aylmer and Artillery lakes. On the south it presents a less rugged bank, and is entered by a river of its own name, flowing N. for about 300 m. from the W. end of Lake Athabasca. It contains a number of islands, some of which are well wooded. For half the year it is frozen over. Mackenzie river connects it with the Arctic ocean.