Source : Webster's Revised Unabridged Dictionary (1913)

Reformer \Re*form"er\ (r?*f?rm"?r), n.
   1. One who effects a reformation or amendment; one who labors
      for, or urges, reform; as, a reformer of manners, or of
      abuses.

   2. (Eccl.Hist.) One of those who commenced the reformation of
      religion in the sixteenth century, as Luther, Melanchthon,
      Zwingli, and Calvin.

Source : WordNet®

reformer
     n 1: a disputant who advocates reform [syn: {reformist}, {crusader},
           {meliorist}]
     2: an apparatus that reforms the molecular structure of
        hydrocarbons to produce richer fuel; "a catalytic
        reformer"