[KyleGoetz]

chruop So if people started speaking Latin again, would the words from Latin no longer be Italian words? They would just stop being Italian simply because some idiots revived a distinct language?

You'd be hard-pressed to find a word in English that isn't from another language. Only neologisms seem to fit under your definition.

But obviously I'm not going to convince you. I just hope that I can convince other readers on the board.

I think a very simple test is "is the word in the dictionary"-test. If the word is in a Japanese dictionary, it's a Japanese word. If it's in the OED, it's an English word. Etc.