Originally Posted by Ansar Al-'Adl
Judeo-Arabic is a language that was spoken mainly by Jews living in the Arab world. It is written in the "Hebrew script (rather than using Arabic script), often including consonant dots from the Arabic alphabet to accommodate phonemes that did not exist in the Hebrew alphabet."
Once I couldn't understand most of a text I was reading, and had an inclination that it might be Judeo-Arabic, so I had a man I knew who understood some arabic and read it to him. He could understand a little of it as well, and it turned out it had both Hebrew and Arabic elements, so the language is most likely a mixture of the two languages.
During the middle ages, it was a very common language among Jews. Many works were produced by Jewish sages in that language, such the Rambam's Guide for the Perplexed
, Sefer ha-Mitzvot
, his commentary on the Mishnah, and many others. Other sages who wrote their works in Judeo-Arabic in Judah HaLevi, Sa'adia Gaon, Solomon ibn Gabirol, and many others. They were later translated into Hebrew.
Judeo-Arabic, in recent times, was spoken by the Yemenite and Mizrahi Jews who lived in Arabic lands, but since the events that happened between '48-'67 which caused them to immigrate either to Israel or France, the language has had a drastic decline in usage, and is considered an endangered language.