| 1. | a province in S Canada, bordering on the Great Lakes. 8,131,618; 412,582 sq. mi. (1,068,585 sq. km). Capital: Toronto. |
| 2. | Lake, a lake between the NE United States and S Canada, between New York and Ontario province: the smallest of the Great Lakes. 193 mi. (310 km) long; 7540 sq. mi. (19,530 sq. km). |
| 3. | a city in SW California, E of Los Angeles. 88,820. |
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.
Note: The Canadian side of Niagara Falls is in southern Ontario.
Note: Ottawa, Canada's capital, is in southeastern Ontario.
Note: Ontario is the most heavily industrialized, populous, and prosperous province in Canada.
Capital of Ontario, Canada, and the largest city in the province, in southern Ontario on Lake Ontario; the largest city in Canada; a commercial, financial, industrial, and cultural center of Canada.