Undo \Un*do"\, v. t. [AS. und?n. See 1st {Un-}, and Do to
   perform.]
   1. To reverse, as what has been done; to annul; to bring to
      naught.
      
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            What's done can not be undone.        --Shak.
      
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            To-morrow, ere the setting sun,
            She 'd all undo that she had done.    --Swift.
      
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   2. To loose; to open; to take to piece; to unfasten; to
      untie; hence, to unravel; to solve; as, to undo a knot; to
      undo a puzzling question; to undo a riddle. --Tennyson.
      
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            Pray you, undo this button.           --Shak.
      
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            She took the spindle, and undoing the thread
            gradually, measured it.               --Sir W.
                                                  Scott.
      
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   3. To bring to poverty; to impoverish; to ruin, as in
      reputation, morals, hopes, or the like; as, many are
      undone by unavoidable losses, but more undo themselves by
      vices and dissipation, or by indolence.
      
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            That quaffing and drinking will undo you, --Shak.
      
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