ROSCOMMON, a county of Ireland, in the province of Connaught, bounded on the west by the river Suck, on the east by the Shannon, on the north by the Curlew mountains, on the south and south east by the King's county and part of Galway. Its length is 35 miles, its breadth 28. The air of the county, both on the plains and mountains, is healthy; the soil yields plenty of grass with some corn, and feeds numerous herds of cattle. The Curlew mountains on the north are very high and steep; and, till a road with great labour and difficulty was cut through them, were impassable.