Answer:
Groundwater is the word that describes the area below the Earth's surface that fills with water.
Explanation:
The water present on the Eart is categorized into two types based on its location of presence. The water that is above the surface of the Earth is called surface 'surface water', and the one that is present below the surface of the Earth is called groundwater.
Groundwater is found under the Earth's surfaces either because it was trapped in the surface during the formation of the Earth, or because the water on the surface of the Earth simply percolates into the ground.