Ontario: Meaning and Definition of

On•tar•i•o

1. a province in S Canada, bordering on the Great Lakes. 8,131,618; 412,582 sq. mi. (1,068,585 sq. km). Cap.: Toronto.
2. 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.