aquifer

noun

1. An underground layer of water-bearing porous stone, earth, or gravel.

   “The water in the well came from an aquifer.”

   “An aquifer is rock or sediment that holds groundwater – rain that is held below the surface of the soil and collected in empty spaces underground. Aquifers feed rivers to keep their flows at a healthy level, and are also important sources of water when reservoirs or other sources run low.”