The Collaborative International Dictionary of English v.0.48:

palm off \palm` off"\ (p[aum]m), v. t.
   (a) To dispose of fraudulently or deceptively; as, to palm
       off a counterfeit item as genuine. Hence:
   (b) To induce acceptance of (something) by misrepresenting it
       as something better.
       [PJC]

WordNet (r) 3.0 (2006):

palm off
    v 1: sell as genuine, sell with the intention to deceive [syn:
         foist off, palm off, fob off]