a considerable river of Ireland, rising in the Mourne Mountains, traversing Lough Neagh, and flowing into the Atlantic. It is commonly described as two rivers separated by Lough Neagh. The upper Bann has a N.W. course from its source to Lough Neagh, and is navigable for vessels of 50 tons to its junction with the Newry canal, a little above Portadown. The lower flows in a northern direction, and is navigable up to Coleraine for vessels of 200 tons; but the bar at its mouth renders it difficult of access in rough weather. Measured in a direct line, the upper Bann is about 35 miles long, and the lower 30 miles.