What does "expiation" mean?

Expiation: The means by which reparation or atonement for crimes or sins is made; an expiatory sacrifice or offering; an atonement. Those shadowy expiations weak, The blood of bulls and goats. Milton.

Additional senses

  1. 2.An act by which the treats of prodigies were averted among the ancient heathen. [Obs.] Hayward.

Sources