Waterloo is a city in Ontario, Canada. It is the smallest of the three cities in the Regional Municipality of Waterloo, and is adjacent to the larger city of Kitchener. Kitchener and Waterloo are often jointly referred to as Kitchener-Waterloo (K-W), or "the twin cities", although they have separate city governments. There have been several attempts to amalgamate the two cities (sometimes with the city of Cambridge as well), but none has been successful.