Penance

Source: Gossip Girl - 218 - The Age of Dissonance

Definitions:

1. Remorse for your past conduct
2. A Catholic sacrament; repentance and confession and atonement and absolution
3. Voluntary self-punishment in order to atone for some wrongdoing
   

Synonyms:

• penitence
• repentance
• self-abasement
• self-mortification