TOPONYMY - is the study of geographical names. It is derived from the Greek: "topo" meaning place and "onoma" meaning name. It is a sub set of onomastics which is the study of all forms of names. Place names are sometimes called toponyms.
ONTARIO - The name was first applied to the lake (1641) and is traceable to Amerindian sources. It may be a corruption of Onitariio, meaning "beautiful lake", or Kanadario, variously translated as "sparkling" or "beautiful" water. Later European settlers gave the name to the land along the lakeshore and then to an ever extending area. "Old Ontario" was a term sometimes loosely applied to the southern portion of the province. *
* Source: Hamilton, William B. (1978): The Macmillan book of Canadian place names, Macmillan of Canada, Toronto, p. 155.
Ontario may have more than one million lakes that are a hectare in size or greater according to a 1978 study. Approximately 23,000 lakes are officially named.
There are approximately 6,800 officially named freshwater flowing features in Ontario which includes 1,271 rivers, 32 brooks, 5,466 creeks and 58 other features such as drains, streams, etc.
Local usage and not size or other criteria normally determines whether the term “lake” goes before or after the specific part of the name in an official lake name (i.e. Lake Joseph vs Big Trout Lake).