noun

• A village in Walloon Brabant, Belgium; the site of a major military battle in 1815.
• A battle fought at Waterloo, Belgium on June 18, 1815, resulting in the epic, final defeat of Napoleon Bonaparte.
• The name of any of several villages, towns, and cities around the world.
• A place in Canada:
• A rural community in Lunenburg County, Nova Scotia.
• A regional municipality and city in Ontario, Canada.
• A city in La Haute-Yamaska regional county municipality, Estrie, Quebec.
• A number of places in the United States:
• A census-designated place in San Joaquin County, California.
• A city, the county seat of Monroe County, Illinois.
• A town in Grant Township and Smithfield Township, DeKalb County, Indiana.
• A township and unincorporated community therein, in Fayette County, Indiana.
• An unincorporated community in White River Township, Johnson County, Indiana.
• A city, the county seat of Black Hawk County, Iowa.
• A village and town, the county seat of Seneca County, New York.
• A town in Grant County, Wisconsin.
• A town and city therein, in Jefferson County, Wisconsin.
• A number of other townships in the United States, listed under Waterloo Township.
• A number of places in the United Kingdom:
• A district and large railway terminus in central London, England.
• A northern suburb of Poole, Dorset, England (OS grid ref SZ0094).
• Former name of Waterlooville, Hampshire, although Waterloo is still the name of a council ward in Waterlooville for Havant borough.
• A small suburb in Blackburn with Darwen, Lancashire, England (OS grid ref SD6625).
• A suburb of Crosby, Sefton borough, Merseyside, England (OS grid ref SJ3198).
• A small village in Broadland district, Norfolk, England (OS grid ref TG2219).
• A small village in South Norfolk district, Norfolk (OS grid ref TM1479).
• A hamlet in Whixall parish, Shropshire, England (OS grid ref SJ4933).
• An eastern suburb of Huddersfield, Kirklees borough, West Yorkshire, England (OS grid ref SE1716).
• A hamlet in Caerphilly county borough, Wales (OS grid ref ST1988).
• A city in the Western Area of Sierra Leone.
• A place in Australia:
• An inner southern suburb of Sydney, New South Wales.
• A rural locality in the Bundaberg Region, Queensland.
• A settlement in Clare and Gilbert Valleys council area, South Australia.
• A locality in Pyrenees Shire, Victoria.
• A small town in the Shire of Dardanup, Western Australia.
• A suburb of Lower Hutt, New Zealand.
• Often in the term meet one's Waterloo: a notable and decisive defeat following an encounter with a powerful opponent or a problem that is too difficult.