Source : Webster's Revised Unabridged Dictionary (1913)

Blockade \Block*ade"\, v. t. [imp. & p. p. {Blockaded}; p. pr. &
   vb. n. {Blockading}.]
   1. To shut up, as a town or fortress, by investing it with
      troops or vessels or war for the purpose of preventing
      ingress or egress, or the introduction of supplies. See
      note under {Blockade}, n. ``Blockaded the place by sea.''
      --Gilpin.

   2. Hence, to shut in so as to prevent egress.

            Till storm and driving ice blockade him there.
                                                  --Wordsworth.

   3. To obstruct entrance to or egress from.

            Huge bales of British cloth blockade the door.
                                                  --Pope.

Source : WordNet®

blockading
     adj : blocking entrance to and exit from seaports and harbors;
           "the blockading ships prevented delivery of munitions"