The Collaborative International Dictionary of English v.0.48:

Dredger \Dredg"er\ (dr[e^]j"[~e]r), n.
   1. One who fishes with a dredge.
      [1913 Webster]

   2. A dredging machine.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dredger \Dredg"er\, n. (Cookery)
   A box with holes in its lid; -- used for sprinkling flour, as
   on meat or a breadboard; -- called also dredging box,
   drudger, and drudging box.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dredger
    n 1: a barge (or a vessel resembling a barge) that is used for
         dredging