What term describes water that fills the cracks and spaces in underground soil and rock layers?

The term that describes water filling the cracks and spaces in underground soil and rock layers is "groundwater." This is a crucial component of the hydrological cycle, acting as a significant source of water for various ecosystems and human use. Groundwater is stored in aquifers, which are porous rock formations that can hold and transmit water.

In comparison, surface water refers to water found on the earth's surface, such as rivers, lakes, and streams. Rainwater specifically denotes precipitation that falls from the atmosphere and may contribute to surface water and groundwater but does not describe the water that exists underground. Stormwater is related to the water from rain events that flows over the ground surface and can lead to flooding in urban areas. Groundwater, therefore, is the most accurate term for water residing beneath the surface within soil and rock layers.