Penance (noun)

1. An act of self-punishment or self-mortification done as an expression of remorse or repentance for a wrongdoing.
2. A religious rite or ceremony, such as confession and absolution, to obtain forgiveness for sins.

Origin:

From old french pénance, from latin poenitentia, from poenitens, present participle of poenitere ("to repent").

Examples:

1. He did penance for his sins.
2. The priest assigned him a penance.
3. The penance for the sin was to fast for a week.
4. Penance was seen as a way to atone for one's sins.
5. The penance was difficult, but he felt it was necessary for his spiritual growth.