aquifer

This term describes a geological formation that acts as a natural sponge, storing water in the pores of rock or sediment. It is primarily used in environmental science, hydrology, and urban planning to discuss sustainable water management and the risks of over-extraction. Because it refers to a specific type of geological layer, it is treated as a standard countable noun. It is often paired with adjectives like confined or unconfined to specify whether the water layer is trapped between impermeable rock or open to the surface.