[1] : WordNet (r) 2.0

centrist
     adj : supporting or pursuing a course of action that is neither
           liberal nor conservative syn: middle-of-the-road
     n : a person who takes a position in the political center syn:
         middle of the roader, moderate, moderationist
see also:
middle-of-the-road middle of the roader moderate moderationist 

[2] : Moby Thesaurus II by Grady Ward, 1.0

29 moby thesaurus words for "centrist":
   laodicean, apathetic, center, compromiser, conservative, even,
   fifty-fifty, half-and-half, impartial, independent, indifferent,
   middle-of-the-road, middle-of-the-roader, midway, moderantist,
   moderate, moderationist, moderatist, neuter, neutral, nonaligned,
   noncommitted, nonpartisan, on the fence, passive, third-force,
   third-world, uncommitted, uninvolved

Centrist >> C Words
Centrist, definition of term: Centrist
centrist_pag1.html