Ontario

American  

[on-tair-ee-oh] / ɒnˈtɛər iˌoʊ /

noun

1. a province in southern Canada, bordering on the Great Lakes. 412,582 square miles (1,068,585 square kilometers). Toronto.

2. Lake Ontario, a lake between the northeastern United States and southern Canada, between New York and Ontario province: the smallest of the Great Lakes. 193 miles (310 kilometers) long; 7,540 square miles (19,530 square kilometers).

3. a city in southwestern California, east of Los Angeles.

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Ontario British  

/ ɒnˈtɛərɪəʊ /

noun

1. Abbreviation: Ont., ON. a province of central Canada: lies mostly on the Canadian Shield and contains the fertile plain of the lower Great Lakes and the St Lawrence River, one of the world's leading industrial areas; the second largest and the most populous province. Capital: Toronto. Pop: 12 392 721 (2004 est). Area: 891 198 sq km (344 092 sq miles)

2. a lake between the US and Canada, bordering on New York State and Ontario province: the smallest of the Great Lakes; linked with Lake Erie by the Niagara River and Welland Canal; drained by the St Lawrence. Area: 19 684 sq km (7600 sq miles)

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Ontario Cultural  

1. Province in central Canada, bordered by Hudson Bay and James Bay to the north; Quebec to the east; the St. Lawrence River, Lake Ontario, Lake Erie, Lake Huron, Lake Superior, and Minnesota to the south; and Manitoba to the west. Its capital and largest city is Toronto.

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Discover More

Ontario is the most heavily industrialized, populous, and prosperous province in Canada.

The Canadian side of Niagara Falls is in southern Ontario.

Ottawa, Canada's capital, is in southeastern Ontario.

Other Word Forms

• Ontarian
  adjective
• Ontaric
  adjective

Example Sentences

See Examples For:

Ontario

"That's nearly four times that of British Columbia, more than four times Ontario," Hill tells the BBC.

From BBC ● Oct. 7, 2026

No cause of death was provided, but she had reportedly canceled a number of performances in Ontario, Canada, in September “due to a serious medical condition.”

From Los Angeles Times ● Oct. 5, 2026

Police in Ontario, Canada, have charged a woman with 65 offences including fraud and theft for allegedly stealing from patients and staff at several healthcare centres in the province.

From BBC ● Sep. 27, 2026

The project brought together researchers from the Wellcome Sanger Institute, U of G's Ontario Veterinary College, the University of Bern and other institutions.

From Science Daily ● Sep. 27, 2026

The weather lady says it’s a lake-effect storm—the wind from Canada sucks up water from Lake Ontario, runs it through the freeze machine, and dumps it on Syracuse.

From "Speak" by Laurie Halse Anderson