The Collaborative International Dictionary of English v.0.48:

Shackle \Shac"kle\, v. t. [imp. & p. p. Shackled; p. pr. & vb.
   n. Shackling.]
   1. To tie or confine the limbs of, so as to prevent free
      motion; to bind with shackles; to fetter; to chain.
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            To lead him shackled, and exposed to scorn
            Of gathering crowds, the Britons' boasted chief.
                                                  --J. Philips.
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   2. Figuratively: To bind or confine so as to prevent or
      embarrass action; to impede; to cumber.
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            Shackled by her devotion to the king, she seldom
            could pursue that object.             --Walpole.
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   3. To join by a link or chain, as railroad cars. [U. S.]
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   Shackle bar, the coupling between a locomotive and its
      tender. [U.S.]

   Shackle bolt, a shackle. --Sir W. Scott.
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WordNet (r) 3.0 (2006):

shackled
    adj 1: bound by chains fastened around the ankles [syn:
           fettered, shackled]