The Judæo-Arabic languages are a collection of Arabic dialects spoken by Jews living or formerly living in the Arab world; the term also refers to more or less classical Arabic written in the Hebrew script, particularly in the Middle Ages. Just as with the rest of the Arab world, Arabic-speaking Jews had different dialects depending on where they lived. This phenomenon may be compared to cases such as different forms of Yiddish (Judæo-German) such as Western Yiddish and Eastern Yiddish, or forms of Ladino (Judæo-Spanish) in areas such as the Balkans, Thessaloníki/Istanbul, Morocco, etc.
The Arabic spoken by Jewish communities in the Arab world differed from the Arabic of their Muslim neighbours, as well as from the Arabic spoken by Christians. These differences were partly due to the incorporation of some words from Hebrew and other languages and partly geographically, in a way that may reflect a history of migration. For example, the Judeo-Arabic of Egypt, including in the Cairo community, resembled the dialect of Alexandria, which shares the first person singular imperfective initial Nun with Maghrebi Arabic dialects (Moroccan, Algerian, Tunisian) rather than the initial Alif of other Egyptian Arabic vernaculars. Similarly the Jewish Iraqi Arabic of Baghdad was found reminiscent of the dialect of Mosul, which in some ways resembles Syrian Arabic rather than Baghdad Arabic or Gulf Arabic. For example, "I said" is qeltu in the speech of Baghdadi Jews and Christians, as well as in Mosul and Syria, as against Muslim Baghdadi gilit. Many Jews in Arab countries were bilingual in Judeo-Arabic and the dialect of the Arab Muslim majority.
Jews in Arab countries wrote—sometimes in their dialects, sometimes in a more classical style—in a mildly adapted 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.
Some of the most important books of medieval Jewish thought were originally written in medieval Judæo-Arabic, as well as certain halakhic works and biblical commentaries. Only later were they translated into medieval Hebrew so that they could be read by the Ashkenazi Jews of Europe. These include:
Most communities also had a traditional translation of the Bible into Judeo-Arabic, known as a sharħ (meaning). The term sharħ sometimes came to mean "Judeo-Arabic" as such, in the same way that "Targum" was sometimes used to mean Aramaic.
In the years following the 1948 Arab-Israeli War, most Mizrahi and Sephardi Jews in Arab countries became Jewish refugees, fleeing mainly to France and Israel. Their dialects of Arabic did not thrive in either country, and most of their descendants now speak French or Modern Hebrew; as a result, the Judæo-Arabic dialects are now considered endangered languages.