Source : Webster's Revised Unabridged Dictionary (1913)

Dam \Dam\, v. t. [imp. & p. p. {Dammed}; p. pr. & vb. n.
   {Damming}.]
   1. To obstruct or restrain the flow of, by a dam; to confine
      by constructing a dam, as a stream of water; -- generally
      used with in or up.

            I'll have the current in this place dammed up.
                                                  --Shak.

            A weight of earth that dams in the water.
                                                  --Mortimer.

   2. To shut up; to stop up; to close; to restrain.

            The strait pass was dammed With dead men hurt
            behind, and cowards.                  --Shak.

   {To dam out}, to keep out by means of a dam.

Source : WordNet®

dammed
     See {dam}

dam
     n 1: a barrier constructed to contain the flow of water or to
          keep out the sea [syn: {dike}, {dyke}, {levee}]
     2: a metric unit of length equal to ten meters [syn: {decameter},
         {dekameter}, {decametre}, {dekametre}, {dkm}]
     3: female parent of an animal especially domestic livestock
     [also: {damming}, {dammed}]

dam
     v : obstruct with, or as if with, a dam; "dam the gorges of the
         Yangtse River" [syn: {dam up}]
     [also: {damming}, {dammed}]