MONAGHAN, a county of Ireland, situated in the province of Ulster, is bounded by Tyrone on the north, Armagh on the east, Cavan and Louth on the south, and Fermanagh on the west. It is a mountainous tract, but in some places is well improved. It contains 170,000 Irish plantation acres, and is about 30 miles long and 22 broad. It has a considerable linen trade, and sends two members to parliament.