The Collaborative International Dictionary of English v.0.48:

Putrefy \Pu"tre*fy\, v. t. [Written also putrify.] [imp. & p. p.
   Putrefied; p. pr. & vb. n. Putrefying.] [F. putr['e]fier;
   L. putrere to be rotten + -ficare (in. comp.) to make; cf. L.
   putrefacere. See Putrid, and -fy.]
   1. To render putrid; to cause to decay offensively; to cause
      to be decomposed; to cause to rot.
      [1913 Webster]

   2. To corrupt; to make foul.
      [1913 Webster]

            Private suits do putrefy the public good. --Bacon.
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            They would but stink, and putrefy the air. --Shak.
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   3. To make morbid, carious, or gangrenous; as, to putrefy an
      ulcer or wound.
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The Collaborative International Dictionary of English v.0.48:

Putrefy \Pu"tre*fy\, v. i.
   To become putrid; to decay offensively; to rot. --Isa. 1. 6.
   [1913 Webster]

WordNet (r) 3.0 (2006):

putrefy
    v 1: become putrid; decay with an offensive smell; "organic
         matter putrefies"