The Collaborative International Dictionary of English v.0.48:

Cozen \Coz"en\, v. i.
   To deceive; to cheat; to act deceitfully.
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         Some cogging, cozening slave.            --Shak.
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The Collaborative International Dictionary of English v.0.48:

Cozen \Coz"en\ (k?z"'n), v. t. [imp. & p. p. Cozened (-'nd);
   p. pr. & vb. n. Cozening (-'n-?ng). ] [From cousin, hence,
   literally, to deceive through pretext of relationship, F.
   cousiner.]
   To cheat; to defraud; to beguile; to deceive, usually by
   small arts, or in a pitiful way.
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         He had cozened the world by fine phrases. --Macaulay.
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         Children may be cozened into a knowledge of the
         letters.                                 --Locke.
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         Goring loved no man so well but that he would cozen
         him,
         and expose him to public mirth for having been cozened.
                                                  --Clarendon.
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WordNet (r) 3.0 (2006):

cozen
    v 1: be false to; be dishonest with [syn: deceive, lead on,
         delude, cozen]
    2: act with artful deceit
    3: cheat or trick; "He cozened the money out of the old man"