penance

noun

• 1voluntary self-punishment inflicted as an outward expression of repentance for having done wrong:he had done public penance for those hasty words

• 2a Christian sacrament in which a member of the Church confesses sins to a priest and is given absolution. In the Roman Catholic Church often called sacrament of reconciliation.
• a religious observance or other duty required of a person by a priest as part of this sacrament to indicate repentance.

verb

• impose a penance on:a hair shirt to penance him for his folly in offending