Monongahela River

American Heritage® Dictionary of the English Language, Fourth Edition

1. A river rising in northern West Virginia and flowing about 206 km (128 mi) generally north into southwest Pennsylvania, where it joins the Allegheny River at Pittsburgh to form the Ohio River.

WordNet 3.0

1. n. a river that rises in northern West Virginia and flows north into Pennsylvania where it joins the Allegheny River at Pittsburgh to form the Ohio River