originally the name of the lake, probably from Ojibwa (Algonquian) winipeg "dirty water;" compare winad "it is dirty." Etymologically related to Winnebago.
Entries linking to winnipeg
Winnebago
"Siouan people of eastern Wisconsin," 1766, from Potawatomi winepyekoha, literally "person of dirty water," in reference to the muddy or fish-clogged waters of the Fox River below Lake Winnebago. As a type of motor vehicle, attested from 1966.