The Collaborative International Dictionary of English v.0.48:

Powdery \Pow"der*y\, a.
   1. Easily crumbling to pieces; friable; loose; as, a powdery
      spar.
      [1913 Webster]

   2. Sprinkled or covered with powder; dusty; as, the powdery
      bloom on plums.
      [1913 Webster]

   3. Resembling powder; consisting of powder. "The powdery
      snow." --Wordsworth.
      [1913 Webster]

WordNet (r) 3.0 (2006):

powdery
    adj 1: consisting of fine particles; "powdered cellulose";
           "powdery snow"; "pulverized sugar is prepared from
           granulated sugar by grinding" [syn: powdered,
           powdery, pulverized, pulverised, small-grained,
           fine-grained]
    2: as if dulled in color with a sprinkling of powder; "a powdery
       blue"

Moby Thesaurus II by Grady Ward, 1.0:

36 Moby Thesaurus words for "powdery":
   branny, chalklike, chalky, comminute, comminuted, crushed,
   detrital, detrited, disintegrated, dusty, efflorescent,
   farinaceous, fine, flaky, floury, furfuraceous, gone to dust,
   grated, ground, impalpable, levigated, mealy, milled, pestled,
   powdered, pulverant, pulverized, pulverulent, reduced to powder,
   scaly, scobicular, scobiform, scurfy, sharded, shredded,
   triturated