What is it called when a river and bay meet?

There isn't a specific, universally accepted term for where a river and bay meet. However, depending on the specific context, a few terms might be used:

* River mouth: This is the most common term and refers to the point where a river flows into a larger body of water, be it a bay, ocean, lake, or another river.

* Estuary: This is a specific type of river mouth where the river meets the sea and fresh water mixes with saltwater. Estuaries often have unique ecosystems due to this mixing.

* Inlet: This term is more general and can describe any narrow body of water that connects a larger body of water to the land, including where a river meets a bay.

Ultimately, the best term to use would depend on the specific geographical features and the context of the discussion.