Oconomowoc is a city in Waukesha County, Wisconsin, United States. Oconomowoc was derived from Coo-no-mo-wauk. This was the Pottawatomie term for distinguishing a waterfall in the vicinity. The population was 12,382 at the 2000 census. The city is located partially within the Oconomowoc township. There is also the nearby Village of Oconomowoc Lake and Town of Oconomowoc.