Final answer:
A "drainage basin" and "watershed" both describe regions where all collected water flows into a shared outlet, such as a river. They play a critical role in the hydrological cycle.
Step-by-step explanation:
The term "drainage basin" is an appropriate synonym for "watershed" because both refer to areas of land where precipitation gathers and flows into a common outlet, such as a river, lake, or the ocean. A drainage basin encompasses all the land that contributes water to a particular river system via various forms including surface runoff and groundwater seepage. These basins are separated from each other by topographic divides which essentially designate the boundaries of a watershed. As an essential element of the hydrological cycle, the water that is collected within a drainage basin eventually makes its way to larger bodies of water, often providing crucial resources like drinking water and irrigation for agriculture.