The Collaborative International Dictionary of English v.0.48:

nonstarter \nonstarter\ n.
   1. a person with a record of failing.

   Syn: loser, failure, unsuccessful person.
        [WordNet 1.5]

   2. A horse that fails to run in a race for which it has been
      entered.
      [WordNet 1.5]

   3. A proposal that will not receive serious consideration by
      those with authority to decide.
      [PJC] nonstick

WordNet (r) 3.0 (2006):

nonstarter
    n 1: a person with a record of failing; someone who loses
         consistently [syn: failure, loser, nonstarter,
         unsuccessful person] [ant: achiever, succeeder,
         success, winner]
    2: a horse that fails to run in a race for which it has been
       entered