- a series of five lakes between the United States and Canada, comprising Lakes Erie, Huron, Michigan, Ontario, and Superior; connected with the Atlantic Ocean by the St. Lawrence River.
- a group of five lakes in central North America with connecting waterways: the largest group of lakes in the world: consists of Lakes Superior, Huron, Erie, and Ontario, which are divided by the border between the US and Canada and Lake Michigan, which is wholly in the US; constitutes the most important system of inland waterways in the world, discharging through the St Lawrence into the Atlantic. Total length: 3767 km (2340 miles). Area: 246 490 sq km (95 170 sq miles)
