1. A member of a Western Christian church whose faith and practice are founded on the principles of the Reformation,especially in the acceptance of the Bible as the sole source of revelation, in justification by faith alone, and in the universal priesthood of all the believers.
2. A member of a Western Christian church adhering to the theologies of Luther, Calvin, or Zwingli.
3. One of the German princes or cities that supported the doctrines of Luther and protested against the decision of the second Diet of Speyer (1529) to enforce the Edict of Worms (1521) and deny toleration to Lutherans.
4. protestant (also prə-tĕs′tənt) One who makes a declaration or avowal.
Of or relating to Protestants or Protestantism.