All Arabic is not the same, it's not always even interunderstandable so it's important to distinguish which dialect you are referring to.

But I did not not know about them, and I did search. Perhaps Google doesn't either.

I understand that. Just from reading your comment I didn't know whether you were referring to the dead language, a nonexistent one, or the dialect...I'll go sit with the rest of the pedants ;)

Arabic has variants. Each Arabic country speaks a different variant, many words are changed. For example, in Tunisia, a good number of our daily used words are from French.

But that language is only used in public; books and newspapers uses the original language.

You mean like english? And all languages?

No, for English and French (the one I know), someone who understands the original language, can figure out most of the spoken language. However, for the variant of Arabic they can fail. My mother told me that in Kuwait native sellers turn to the original Arabic in order to be understood.