Athabasca, Or Athapcscow. I. A lake of British North America, in lat. 59° N., and between lon. 106° and 112° W., about midway between the Rocky mountains and Hudson bay. It is about 20 m. wide from N. to S. and 230 m. long. Ports Chipewyan and Fond du Lac are on its N. shore. At the W. end it receives the Athabasca and Peace rivers, and discharges the Slave river, which flows N. into Great Slave lake, whence there is communication by the Mackenzie river with the Arctic ocean. The Black river issues from its E. extremity, and forms part of the channel through which, by Black, Manito or Wollaston, Deer, and Indian lakes, and the Churchill river, it is connected with Hudson bay. II. A river which rises in the Rocky mountains, near Mt. Brown, in lat. 52° 10' N., lon. 116° 30' W., and has a tortuous N. and N. E. course, receiving the overflow of the Lesser Slave and several other lakes, and entering Athabasca lake. Its length is about 600 m. A shoal seyeral miles in extent is formed by the debris and drift timber which it brings into the lake.