estuary
Definitions
The tidal mouth of a large river, where the tide meets the stream.
A partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.
Examples
The river widens as it flows into the estuary, creating a rich habitat for various species of fish and birds.
We spent the afternoon kayaking through the calm waters of the estuary, observing the unique wildlife along the marshy banks.