EX'PIATE, verb transitive [Latin expio; ex and pio, to worship, to atone; pius, pious, mild. The primary sense is probably to appease, to pacify, to allay resentment, which is the usual sense of atone in most languages which I have examined. Pio is probably contracted from pico, and from the root of paco, the radical sense of which is to lay, set or fix; the primary sense of peace, pax. Hence the sense of mild in pius. But this opinion is offered only as probable.
1. To atone for; to make satisfaction for; to extinguish the guilt of a crime by subsequent acts of piety or worship, by which the obligation to punish the crime is canceled. To expiate guilt or a crime, is to perform some act which is supposed to purify the person guilty; or some act which is accepted by the offended party as satisfaction for the injury; that is, some act by which his wrath is appeased, and his forgiveness procured.
2. To make reparation for; as, to expiate an injury.
3. To avert the threats of prodigies.