OUSE, a river of England, county of York, is formed by the junction of the Swale and the Ure, which unite near Borough Bridge. It flows through the great plain of Yorkshire, at first S.E. as far as the town of York, which it passes, and then pursues an irregular course S. and S.E., until it joins with the Trent to form the estuary of the Humber, by which it discharges its waters into the German Ocean. It receives the Nidd, the Wharfe, and the Don, from the left, and the Derwent from the right. Its whole length is about 60 miles; and it is navigable for large vessels up to York, 45 miles from its mouth.