Past tense: made amends for or atoned for a wrongdoing or sin.
Past participle of expiate, from Latin expiatus, following the regular Latin -atus ending for past participles. The word maintains its meaning of making ceremonial or moral atonement since Roman times.
In literature, characters 'expiate' their sins through dramatic suffering—think of how Greek tragedy uses punishment as a form of moral cleansing, which is the essence of what this word captures.
Complete word intelligence in one call. Free tier — 50 lookups/day.