Definitions of shackle:

• noun:   a restraint that confines or restricts freedom (especially something used to tie down or restrain a prisoner)
• noun:   a U-shaped bar; the open end can be passed through chain links and closed with a bar
• verb:   restrain with fetters
• verb:   bind the arms of
• name:  A surname (very rare: popularity rank in the U.S.: #60344)