allegheny

noun

1. a river flowing NW from Pennsylvania into SW New York and then S through W Pennsylvania, joining the Monongahela at Pittsburgh to form the Ohio River. 325 miles (525 km) long.

plural noun

1. a mountain range in Pennsylvania, Maryland, West Virginia, and Virginia: a part of the Appalachian Mountains.

pl n

1. a mountain range in Pennsylvania, Maryland, Virginia, and West Virginia: part of the Appalachian system; rising from 600 m (2000 ft) to over 1440 m (4800 ft)