Naperville (nāˈpərvĭl) [key], city (1990 pop. 85,351), Du Page co., NE Ill., on the Du Page River, in a farm area; settled 1831–32, inc. as a city 1890. It is a major office and corporate center that grew markedly in the late 20th cent. Manufactures include metal, food, paper, and plastic products; electrical equipment; machinery; and medical supplies. Naperville is the seat of North Central College.