Merriam-Webster's Collegiate® Dictionary, 11th Edition
PENANCE
I. noun
Etymology: Middle English, from Anglo-French, from Medieval Latin poenitentia penitence
Date: 14th century
an act of self-abasement, mortification, or devotion performed to show sorrow or repentance for sin, a sacramental rite that is practiced in Roman, Eastern, and some Anglican churches and that consists of private confession, absolution, and a penance directed by the confessor, something (as a hardship or penalty) resembling an act of penance (as in compensating for an offense),
II. transitive verb (penanced; penancing)
Date: circa 1600
to impose penance on