Yiddish. Spoken in countries all over the world (no specific nationality) by around three million. More at Wikipedia and Omniglot.
An interesting video of a man speaking Yiddish and talking about the language and its history and current status. I would like to learn Yiddish. I’m not Jewish and have no affiliation with anything Hebrew/Yiddish/Jewish/Israel-related, but I think Yiddish is interesting. This book and this dictionary look the best; they’re by a very well-related author.










