The Collaborative International Dictionary of English v.0.48:

Repentance \Re*pent"ance\ (r[-e]*p[e^]nt"ans), n. [F.
   repentance.]
   The act of repenting, or the state of being penitent; sorrow
   for what one has done or omitted to do; especially,
   contrition for sin. --Chaucer.
   [1913 Webster]

         Godly sorrow worketh repentance to salvation. --2. Cor.
                                                  vii. 20.
   [1913 Webster]

         Repentance is a change of mind, or a conversion from
         sin to God.                              --Hammond.
   [1913 Webster]

         Repentance is the relinquishment of any practice from
         the conviction that it has offended God. Sorrow, fear,
         and anxiety are properly not parts, but adjuncts, of
         repentance; yet they are too closely connected with it
         to be easily separated.                  --Rambler.
   [1913 Webster]

   Syn: Contrition; regret; penitence; contriteness;
        compunction. See Contrition.
        [1913 Webster]

WordNet (r) 3.0 (2006):

repentance
    n 1: remorse for your past conduct [syn: repentance,
         penitence, penance]

The Devil's Dictionary (1881-1906):

REPENTANCE, n.  The faithful attendant and follower of Punishment.  It
is usually manifest in a degree of reformation that is not
inconsistent with continuity of sin.

    Desirous to avoid the pains of Hell,
    You will repent and join the Church, Parnell?
    How needless! -- Nick will keep you off the coals
    And add you to the woes of other souls.
                                                         Jomater Abemy