A large natural stream, which may be a waterway.
A river??
A tributary.
River, stream, waterway, brook, canal, or watercourse
river
its called absorbation
An ocean current.
A large stream of surface water is usually called a river. A river is freshwater and runs from high to low ground.
A current. A rotating current is called a gyre.
A Tributary
tributary
A stream or river called that flows into a larger stream or river is called a tributary.