|—n , pl -aries|
|1.||the widening channel of a river where it nears the sea, with a mixing of fresh water and salt (tidal) water|
|2.||an inlet of the sea|
|[C16: from Latin aestuārium marsh, channel, from aestus tide, billowing movement, related to aestās summer]|
A wide body of water formed where a large river meets the sea. It contains both fresh and salt water.