What is it called when two or more bodies of water meet?

A confluence occurs when two or more flowing bodies of water join together to form a single channel. Confluences occur where a tributary joins a larger river, where two rivers join to create a third, or, where two separated channels of a river, having formed an island, rejoin downstream. Confluences are important to the ecology of a stream because they often mark where changes in river energy, chemistry, and habitat take place.

Source: USGS