Wauwatosa, city, Milwaukee County, southeastern Wisconsin, on the Menomonee River, an industrial and residential community near Milwaukee; incorporated as a city 1897. Manufactures include engines and motorcycles. Distribution and medical services also employ many people. A church designed by Frank Lloyd Wright is here. The name of the community (settled in 1835) is probably derived from that of a Potawatomi leader. Population 51,308 (1980); 49,366 (1990); 47,271 (2000).