DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   Leach \Leach\, v. t. [imp. & p. p. Leached; p. pr. & vb. n.
      Leaching.] [Written also leech and letch.]
      1. To remove the soluble constituents from by subjecting to
         the action of percolating water or other liquid; as, to
         leach ashes or coffee.
         [1913 Webster]
      2. To dissolve out; -- often used with out; as, to leach out
         alkali from ashes.
         [1913 Webster]