Source : Webster's Revised Unabridged Dictionary (1913)

Penance \Pen"ance\, n. [OF. penance, peneance, L. paenitentia
   repentance. See {Penitence}.]
   1. Repentance. [Obs.] --Wyclif (Luke xv. 7).

   2. Pain; sorrow; suffering. [Obs.] ``Joy or penance he
      feeleth none.'' --Chaucer.

   3. (Eccl.) A means of repairing a sin committed, and
      obtaining pardon for it, consisting partly in the
      performance of expiatory rites, partly in voluntary
      submission to a punishment corresponding to the
      transgression. Penance is the fourth of seven sacraments
      in the Roman Catholic Church. --Schaff-Herzog Encyc.

            And bitter penance, with an iron whip. --Spenser.

            Quoth he, ``The man hath penance done, And penance
            more will do.''                       --Coleridge.

Penance \Pen"ance\, v. t. [imp. & p. p. {Penanced}.]
   To impose penance; to punish. ``Some penanced lady elf.''
   --Keats.

Source : WordNet®

penance
     n 1: remorse for your past conduct [syn: {repentance}, {penitence}]
     2: a Catholic sacrament; repentance and confession and
        satisfaction and absolution
     3: voluntary self-punishment in order to atone for some
        wrongdoing [syn: {self-mortification}, {self-abasement}]