Noun 1. expiation - compensation for a wrong; "we were unable to get satisfaction from the local store" atonement, satisfaction amends, damages, indemnification, redress, restitution, indemnity - a sum of money paid in compensation for loss or injury
2. expiation - the act of atoning for sin or wrongdoing (especially appeasing a deity) atonement, propitiation redemption, salvation - (theology) the act of delivering from sin or saving from evil amends, reparation - something done or paid in expiation of a wrong; "how can I make amends"
Enough said ...
You said, ignorantly, that St. Paul does not teach purgatory; I however, showed to you where he does, and then gave you authoritative teaching on what purgatory is. The teaching of St. Paul matches the teaching of the Church on the purgatory.
If you wish to drop that topic and instead tell me what the Catechism, in your opinion, says, you need to find someone interested in your thoughts and with time to listen. I have other things to do.