aquifer

from WordNet (r) 3.0 (2006)

aquifer
    n 1: underground bed or layer yielding ground water for wells
         and springs etc

from The Collaborative International Dictionary of English v.0.48

aquifer \aquifer\ n.
   1. an underground bed or layer yielding ground water for
      wells and springs etc.; as, the Oglala aquifer. The water
      contained in an aquifer may be of great age, and in such
      cases is sometimes called

   {fossil water}.
      [WordNet 1.5 +PJC]