1) what is wiped off
 2) dirt rubbed off
 3) off scouring, scrapings

 The Athenians, in order to avert public calamities, yearly threw a
 criminal into the sea as an offering to Poseidon; hence the term
 became used for an expiatory offering, a ransom, for our child, i.e.
 in comparison with the saving of our son's life let it be to us a
 despicable and worthless thing. It is used of a man who in behalf of
 religion undergoes dire trials for the salvation of others.