The Collaborative International Dictionary of English v.0.48:

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.
      [1913 Webster]

   2. Hence, to shut in so as to prevent egress.
      [1913 Webster]

            Till storm and driving ice blockade him there.
                                                  --Wordsworth.
      [1913 Webster]

   3. To obstruct entrance to or egress from.
      [1913 Webster]

            Huge bales of British cloth blockade the door.
                                                  --Pope.
      [1913 Webster]

WordNet (r) 3.0 (2006):

blockading
    adj 1: blocking entrance to and exit from seaports and harbors;
           "the blockading ships prevented delivery of munitions"