Monaghan (mŏnˈəhən, –hănˌ) [key], county (1991 pop. 51,293), 498 sq mi (1,290 sq km), N Republic of Ireland, bordered on the N by Northern Ireland. The county seat is Monaghan. The northwest portion of the county is a part of the fertile central plain of Ireland; to the south and east are hilly sections. It is primarily an agricultural county. The main enterprise is the raising of beef and dairy cattle. Potatoes, oats, and turnips are the chief crops; pigs, sheep, and poultry, as well as cattle, are raised in large numbers. Other industries are bacon curing and the manufacture of furniture and footwear.