The Collaborative International Dictionary of English v.0.48:

Driftwood \Drift"wood`\, n.
   1. Wood drifted or floated by water.
      [1913 Webster]

   2. Fig.: Whatever is drifting or floating as on water.
      [1913 Webster]

            The current of humanity, with its heavy proportion
            of very useless driftwood.            -- New Your
                                                  Times.
      [1913 Webster]

WordNet (r) 3.0 (2006):

driftwood
    n 1: wood that is floating or that has been washed ashore