"I don't know the answer, but along the same lines...why is Jack "short" for John? Someone help us!"
I'm so glad to have found this discussion because I love the etymology of names. (Let me warn you that this is just speculation; do not take this for absolute truth but just my theory- nor do I guarantee that my spelling of the ancient names is correct.) As for Jack, that one is very interesting. As far as I can tell, it is derivitive more of Jacob than of John. The Hebrew name Yaakov was transliterated into Greek as Iakobos. This name then took many different paths. It turned into the various forms of Jacob, on the one hand, but in many dialects of Italian it became not just Giaccopo but Giaccomo. In French, these became Jacques, but in English, Giaccomo became James. That's why the letter of "Iacobos" in the New Testament is translated as the letter of "James." I always had thought, then, that Jack, which is like Jacques, was a nickname for James.
Perhaps the John/Jack relation is, indeed, due to mixing up "Jean" and "Jacques" in the French name Jean-Jacques, as much of the English language is adapted French. But perhaps it hearkens back to the original Hebrew name, Iokannon, from which the Greek "Ioannes" is derived, and consequently all of the modern European equivalents. But this is unlikely.
If I'm incorrect or if anyone has more complete information, your input is much desired.
