The Collaborative International Dictionary of English v.0.48:

Seine \Seine\, n. [F. seine, or AS. segene, b?th fr. L. sagena,
   Gr. ????.] (Fishing.)
   A large net, one edge of which is provided with sinkers, and
   the other with floats. It hangs vertically in the water, and
   when its ends are brought together or drawn ashore incloses
   the fish.
   [1913 Webster]

   Seine boat, a boat specially constructed to carry and pay
      out a seine.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Seine
    n 1: a French river that flows through the heart of Paris and
         then northward into the English Channel [syn: Seine,
         Seine River]
    2: a large fishnet that hangs vertically, with floats at the top
       and weights at the bottom
    v 1: fish with a seine; catch fish with a seine

The Devil's Dictionary (1881-1906):

SEINE, n.  A kind of net for effecting an involuntary change of
environment.  For fish it is made strong and coarse, but women are
more easily taken with a singularly delicate fabric weighted with
small, cut stones.

    The devil casting a seine of lace,
        (With precious stones 'twas weighted)
    Drew it into the landing place
        And its contents calculated.

    All souls of women were in that sack --
        A draft miraculous, precious!
    But ere he could throw it across his back
        They'd all escaped through the meshes.
                                                      Baruch de Loppis