And...pretend I put something clever here.
I figure by now, everyone’s hurting coming up with posts. So, pain.
Pain first showed up as a noun in the late thirteenth century, where it meant punishment, usually for a crime, as well as the definition we know it as. It comes from the Old French peine, suffering or punishment, and before that the classical Latin poena, penalty or punishment. Poena is also where subpoena comes from. I guess that makes it “under penalty”. Anyway, like many things, the Romans took that word from Greek, where the word poini means penalty. From there, it can be traced even further back to the Proto Indo European kwei, pay or atone. No, I don’t know why the k changed to a p. Peer pressure?
University of Texas at Austin Linguistic Research Center