Roscommon (rŏskŏmˈən) [key], county (1991 pop. 51,876), 951 sq mi (2,463 sq km), central Republic of Ireland. The county seat is Roscommon. A part of the central plain of Ireland, the region is low-lying and contains many lakes (Lough Allen and Lough Ree) and bogs. The Shannon, which forms the eastern border, and the Suck, which borders the county on the west, are the principal rivers. The economy is primarily dependent on agriculture; cattle and sheep are also raised. Industries and trade have developed. Several coal mines are operated in the northeast.