a group of five lakes along the border between the US and Canada. These lakes are Lake Superior, Lake Michigan, Lake Huron, Lake Erie, and Lake Ontario. They are connected to form the St Lawrence Seaway which can be used by large ships.
Definition from the Longman Dictionary of Contemporary English Advanced Learner's Dictionary.
Dictionary pictures of the day
Do you know what each of these is called?
Click on any of the pictures above to find out what it is called.