'penance' originates from Old French, specifically the word 'penitence,' where 'penit-' meant 'repentance.'

'penitence' transformed into the Middle English word 'penaunce,' and eventually became the modern English word 'penance.'

Initially, it meant 'repentance or remorse,' but over time it evolved into its current meaning of 'an act of self-punishment or devotion.'