The Collaborative International Dictionary of English v.0.48:

Redeemer \Re*deem"er\ (r?*d?m"?r), n.
   1. One who redeems.
      [1913 Webster]

   2. Specifically, the Savior of the world, Jesus Christ.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Redeemer
    n 1: a teacher and prophet born in Bethlehem and active in
         Nazareth; his life and sermons form the basis for
         Christianity (circa 4 BC - AD 29) [syn: Jesus, Jesus of
         Nazareth, the Nazarene, Jesus Christ, Christ,
         Savior, Saviour, Good Shepherd, Redeemer,
         Deliverer]
    2: someone who redeems or buys back (promissory notes or
       merchandise or commercial paper etc.)

Easton's 1897 Bible Dictionary:

Redeemer
   Heb. goel; i.e., one charged with the duty of restoring the
   rights of another and avenging his wrongs (Lev. 25:48, 49; Num.
   5:8; Ruth 4:1; Job 19:25; Ps. 19:14; 78:35, etc.). This title is
   peculiarly applied to Christ. He redeems us from all evil by the
   payment of a ransom (q.v.). (See REDEMPTION.)