Source : Webster's Revised Unabridged Dictionary (1913)

Demurrage \De*mur"rage\, n. [Cf. OF. demorage delay. See
   {Demur}.] (Law)
   (a) The detention of a vessel by the freighter beyond the
       time allowed in her charter party for loading, unloading,
       or sailing.
   (b) The allowance made to the master or owner of the ship for
       such delay or detention.

             The claim for demurrage ceases as soon as the ship
             is cleared out and ready for sailing. --M`Culloch.

   Note: The term is also applied to similar delays and
         allowances in land carriage, by wagons, railroads, etc.

Source : WordNet®

demurrage
     n 1: a charge required as compensation for the delay of a ship or
          freight car or other cargo beyond its scheduled time of
          departure
     2: detention of a ship or freight car or other cargo beyond its
        scheduled time of departure