The Collaborative International Dictionary of English v.0.48:

Double \Dou"ble\, v. i.
   1. To be increased to twice the sum, number, quantity,
      length, or value; to increase or grow to twice as much.
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            'T is observed in particular nations, that within
            the space of three hundred years, notwithstanding
            all casualties, the number of men doubles. --T.
                                                  Burnet.
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   2. To return upon one's track; to turn and go back over the
      same ground, or in an opposite direction.
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            Doubling and turning like a hunted hare. --Dryden.
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            Doubling and doubling with laborious walk.
                                                  --Wordsworth.
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   3. To play tricks; to use sleights; to play false.
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            What penalty and danger you accrue,
            If you be found to double.            --J. Webster.
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   4. (Print.) To set up a word or words a second time by
      mistake; to make a doublet.
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   To double upon (Mil.), to inclose between two fires.
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