The Collaborative International Dictionary of English v.0.48:

Regeneration \Re*gen`er*a"tion\ (-?"sh?n), n. [L. regeneratio:
   cf. F. r['e]g['e]neration.]
   1. The act of regenerating, or the state of being
      regenerated.
      [1913 Webster]

   2. (Theol.) The entering into a new spiritual life; the act
      of becoming, or of being made, Christian; that change by
      which holy affectations and purposes are substituted for
      the opposite motives in the heart.
      [1913 Webster]

            He saved us by the washing of regeneration, and
            renewing of the Holy Chost.           --Tit. iii. 5.
      [1913 Webster]

   3. (Biol.) The reproduction of a part which has been removed
      or destroyed; re-formation; -- a process especially
      characteristic of a many of the lower animals; as, the
      regeneration of lost feelers, limbs, and claws by spiders
      and crabs.
      [1913 Webster]

   4. (Physiol.)
      (a) The reproduction or renewal of tissues, cells, etc.,
          which have been used up and destroyed by the ordinary
          processes of life; as, the continual regeneration of
          the epithelial cells of the body, or the regeneration
          of the contractile substance of muscle.
      (b) The union of parts which have been severed, so that
          they become anatomically perfect; as, the regeneration
          of a nerve.
          [1913 Webster]

WordNet (r) 3.0 (2006):

regeneration
    n 1: (biology) growth anew of lost tissue or destroyed parts or
         organs
    2: feedback in phase with (augmenting) the input [syn: positive
       feedback, regeneration]
    3: the activity of spiritual or physical renewal
    4: forming again (especially with improvements or removal of
       defects); renewing and reconstituting [syn: re-formation,
       regeneration]

Moby Thesaurus II by Grady Ward, 1.0:

78 Moby Thesaurus words for "regeneration":
   Fabianism, adoption, amendment, change of allegiance,
   change of heart, change of mind, circumcision, conversion, copy,
   duplication, extremism, gradualism, imitation, improvement,
   meliorism, new birth, new life, palingenesis, palingenesy,
   progressivism, radical reform, radicalism, re-creation,
   re-formation, reanimation, rebirth, rebuilding, reclamation,
   reconstitution, reconstruction, recrudescence, redeemedness,
   redemption, redesign, redoing, reedition, reestablishment,
   refashioning, reform, reformation, reformism, refreshment,
   regeneracy, regenerateness, regenesis, reinstitution, reissue,
   rejuvenation, rejuvenescence, remaking, renaissance, renascence,
   renewal, renovation, reorganization, repetition, reprinting,
   reproduction, reshaping, restoration, restructuring, resurgence,
   resurrection, resuscitation, revision, revisionism, revival,
   revivescence, revivescency, revivification, revolution, salvation,
   second birth, second wind, second youth, spiritual purification,
   transformation, utopianism



Easton's 1897 Bible Dictionary:

Regeneration
   only found in Matt. 19:28 and Titus 3:5. This word literally
   means a "new birth." The Greek word so rendered (palingenesia)
   is used by classical writers with reference to the changes
   produced by the return of spring. In Matt. 19:28 the word is
   equivalent to the "restitution of all things" (Acts 3:21). In
   Titus 3:5 it denotes that change of heart elsewhere spoken of as
   a passing from death to life (1 John 3:14); becoming a new
   creature in Christ Jesus (2 Cor. 5:17); being born again (John
   3:5); a renewal of the mind (Rom. 12:2); a resurrection from the
   dead (Eph. 2:6); a being quickened (2:1, 5).

     This change is ascribed to the Holy Spirit. It originates not
   with man but with God (John 1:12, 13; 1 John 2:29; 5:1, 4).

     As to the nature of the change, it consists in the implanting
   of a new principle or disposition in the soul; the impartation
   of spiritual life to those who are by nature "dead in trespasses
   and sins."

     The necessity of such a change is emphatically affirmed in
   Scripture (John 3:3; Rom. 7:18; 8:7-9; 1 Cor. 2:14; Eph. 2:1;
   4:21-24).