LOUGH, a lake of Ireland, formed by an expansion of the Shannon, lying between the counties of Longford and Westmeath on the E., and that of Roscommon on the W.; length, from N. to S., about 15 miles; greatest breadth, 8; area, 42 square miles; extreme depth, 75 feet. Its shores are irregular in outline, but extremely beautiful in scenery; and the few islands which the lake contains also possess many attractions. Besides the Shannon, Lough Ree receives the Inny from the east.