Ok, I've got a Baretta (Pietro Baretta) model 84B 9mm short. Not sure of how old it is but, my Pop-Pop gave it to me years ago before he passed and as such will remain in my family forever (I hope).
This gun doesn't say ".380" or ".380 acp" anywhere on it, but that's exactly what it is.
So, in my humble opinion, .380 IS 9mm short. Yes? 😉