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: Webster's Revised Unabridged Dictionary (1913)