The Collaborative International Dictionary of English v.0.48:

Putrescent \Pu*tres"cent\, a. [L. putrescens, p. pr.of
   putrescere to grow rotten, v. incho. fr. putrere to be
   rotten. See Putrid.]
   1. Becoming putrid or rotten.
      [1913 Webster]

            Externally powerful, although putrescent at the
            core.                                 --Motley.
      [1913 Webster]

   2. Of or pertaining to the process of putrefaction; as, a
      putrescent smell.
      [1913 Webster]

WordNet (r) 3.0 (2006):

putrescent
    adj 1: becoming putrid; "a trail lined by putrescent carcasses"