About Pandora’s box, Wikipedia says:
The word translated as box was actually a large jar (πίθος pithos) in Greek. […] Many scholars see a close analogy between Pandora herself, who was made from clay, and the clay jar which dispenses evils.
The mistranslation of pithos is usually attributed to the 16th century humanist Erasmus who, in his Latin account of the story of Pandora, changed the Greek pithos to pyxis, meaning box.
That change really pyxis me off.
But more seriously, this made me wonder whether the two words are related. Looking through etymologies on Wikitionary, it doesn’t seem so, but interestingly, it seems that “pyxis” came from an earlier Greek word “púxos” (πύξος), meaning “boxwood”, but that word in turn might have been a borrowing back from Latin “buxus”.
Which made me wonder about similar cases in modern languages, where a word that originated in one language and was borrowed into another got borrowed back. I’m sure there must be a lot of examples in, say, French -> English -> French. But I don’t know off the top of my head.