The Collaborative International Dictionary of English v.0.48:

Skim \Skim\, a.
   Contraction of Skimming and Skimmed.
   [1913 Webster]

   Skim coat, the final or finishing coat of plaster.

   Skim colter, a colter for paring off the surface of land.


   Skim milk, skimmed milk; milk from which the cream has been
      taken.
      [1913 Webster]

WordNet (r) 3.0 (2006):

skim milk
    n 1: milk from which the cream has been skimmed [syn: skim
         milk, skimmed milk] [ant: whole milk]