Yiddish is the only language spoken in Yiddish. Just like English is the only language spoken in English.

Yiddish is a language. It doesn't really have an antonym.

Harry Coldoff has written:

'A Yiddish dictionary in transliteration' -- subject(s): Dictionaries, English, English language, Yiddish, Yiddish language

No, some Jewish people speak Hebrew and/or Yiddish.

It is important to note that the Yiddish word for Jewish is Yiddish, so the language is actually called "Jewish", but there is no language identified with the English word "Jewish".

Yiddish refers to a language based loosely on German that was spoken by Jews in Central and Eastern Europe. Yiddish is the Yiddish word for "Jewish".