The Collaborative International Dictionary of English v.0.48:

Medalist \Med"al*ist\, n. [Cf. F. m['e]dailliste, It.
   medaglista.] [Written also medallist.]
   [1913 Webster]
   1. A person that is skilled or curious in medals; a collector
      of medals. --Addison.
      [1913 Webster]

   2. A designer of medals. --Macaulay.
      [1913 Webster]

   3. One who has gained a medal as the reward of merit; as, the
      gold medalist in downhill skiing.
      [1913 Webster]

WordNet (r) 3.0 (2006):

medallist
    n 1: someone who has won a medal [syn: medalist, medallist]
    2: (golf) the winner at medal play of a tournament [syn:
       medalist, medallist, medal winner]