Quiz: Remember the definition of mal de mer?
c.1300, "to feel such regret for sins or crimes as produces amendment of life," from Old French repentir (11c.), from re-, here probably an intensive prefix (see re-), + Vulgar Latin *penitire "to regret," from Latin poenitire "make sorry," from poena (see penal). The distinction between regret (q.v.) and repent is made in many modern languages, but the differentiation is not present in older periods. Related: Repented; repenting.