The Collaborative International Dictionary of English v.0.48:

dusty \dust"y\ (d[u^]st"[y^]), a. [Compar. Dustier
   (d[u^]st"[i^]*[~e]r); superl. Dustiest
   (d[u^]st"[i^]*[e^]st).] [AS. dystig. See Dust.]
   1. Filled, covered, or sprinkled with dust; clouded with
      dust; as, a dusty table; a dusty attic; also, reducing to
      dust.
      [1913 Webster]

            And all our yesterdays have lighted fools
            The way to dusty death.               --Shak.
      [1913 Webster]

   2. Like dust; of the color of dust; as, a dusty white.
      [1913 Webster]

   Dusty miller (Bot.), a plant (Cineraria maritima); -- so
      called because of the ashy-white coating of its leaves.
      [1913 Webster]

WordNet (r) 3.0 (2006):

dusty
    adj 1: covered with a layer of dust; "a dusty pile of books"
           [syn: dusty, dust-covered]
    2: lacking originality or spontaneity; no longer new; "moth-
       eaten theories about race"; "stale news" [syn: cold,
       stale, dusty, moth-eaten]