The Collaborative International Dictionary of English v.0.48:

Dam \Dam\, v. t. [imp. & p. p. Dammed (d[a^]md); 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.
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            I'll have the current in this place dammed up.
                                                  --Shak.
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            A weight of earth that dams in the water.
                                                  --Mortimer.
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   2. To shut up; to stop up; to close; to restrain.
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            The strait pass was dammed
            With dead men hurt behind, and cowards. --Shak.
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   To dam out, to keep out by means of a dam.
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