Fond du Lac is a city in Fond du Lac County, Wisconsin, United States. The name is French for bottom (or foot) of the lake, for it is located at the bottom (south end) of Lake Winnebago. The population was 42,203 at the 2000 census. The city borders the Town of Fond du Lac, although a small portion borders other adjacent towns. The city forms the core of the United States Census Bureau's Fond du Lac Metropolitan Statistical Area, which includes all of Fond du Lac County .