Estuary (noun)

1. A place where a river meets the sea, typically where the river is tidal.
2. An arm of the sea at the lower end of a river, usually where the tide meets the current.

Origin:

Late 16th century: from latin aestuarium, from aestus "tide".

Examples:

1. The Amazon River estuary is the largest in the world, and is home to many species of fish and birds.
2. The estuary serves as an important habitat for several species of fish, crustaceans, and mollusks.
3. Salt marshes and tidal creeks can often be found in an estuary.
4. Many towns and cities have been built near estuaries, because they offer easy access to the sea.
5. The estuary provides a unique environment, where freshwater mixes with saltwater and creates a rich habitat.