The Collaborative International Dictionary of English v.0.48:

Polygraphy \Po*lyg"ra*phy\, n. [Gr. ?; poly`s much + gra`fein to
   write: cf. F. polygraphie.]
   1. Much writing; writing of many books. [Obs.] --Fuller.
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   2. The art of writing in various ciphers, and of deciphering
      the same. [R.]
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   3. The art or practice of using a polygraph.
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