Merriam-Webster Collegiate Dictionary - expiate

 verb  (-ated; -ating)  Etymology: Latin expiatus, past participle of expiare to atone for, from ex- + piare to atone for, appease, from pius faithful, pious  Date: circa 1500  transitive verb  1. obsolete to put an end to  2.  a. to extinguish the guilt incurred by  b. to make amends for permission to ~ their offences by their assiduous labours — Francis Bacon  intransitive verb to make expiation  • expiable adjective  • expiator noun