| 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. |
| Ontario, Lake The smallest of the Great Lakes, between southeast Ontario, Canada, and northwest New York. The St. Lawrence Seaway and Welland Ship Canal connect with the lake to afford passage by oceangoing vessels to the other Great Lakes. |