Olean (ōˈlēănˌ) [key], city (1990 pop. 16,946), Cattaraugus co., W N.Y., on the Allegheny River near the Pa. line; settled 1804, inc. 1893. The city formerly had an oil-based economy related to nearby oil wells; manufactures still include turbines and compressors for the oil industry as well as electrical items, cutlery, and dairy products. St. Bonaventure Univ. and Allegheny State Park are nearby. In 1972 a severe flood destroyed close to 3,000 homes.