Besides having been spoken by large portions of Jewry for long periods of history, and being the languages of some of the greatest works of Jewish thought and literature, Arabic and Yiddish would seem to have little in common. But Alexander Jabbari points to shared vocabulary, mutual influence, and much else:
Through modern Hebrew, Yiddish words occasionally find their way into Arabic. A notable example in Palestinian Arabic is balagan, meaning “chaos,” borrowed from Hebrew.
While balagan came to Palestinian Arabic through Hebrew, the source of the Hebrew word was likely Yiddish. The word is ultimately from Persian bālākhāna, meaning “upper room” or “chamber.” It passed from Persian into Tatar or another Turkic language and from there entered Russian as balagan, where it came to refer to a temporary wooden structure for circus performances. Because of the circus context, the Russian word also acquired the connotation of “buffoonery.” When borrowed from Russian and put into Yiddish (and Polish), the chaos of the circus setting gave the word the sense of a mess, bedlam, or chaos.
In Ottoman Palestine, and especially in Jerusalem before 1948, it was common for Yiddish-speaking Jews and Arabs to understand each other’s languages, particularly in neighborhoods where the two communities abutted each other. . . . [I]n the 19th century, there were groups of Ashkenazi men in Jerusalem who learned Arabic, both spoken and literary. Arabic words became part of the everyday Yiddish spoken in Palestine—even for terms specific to Judaism, like khalake, a boy’s ritual first haircut, from the Arabic for haircut, ḥalāqa.
Some Arabic vocabulary even made its way into Yiddish through [more] circuitous routes. Take the Yiddish bakaleyne, meaning “grocery store.” Originally an Arabic word, it traveled through a number of other languages before reaching Yiddish. The Arabic baqqāl, meaning greengrocer, was borrowed by Persian, and from there it followed a similar trajectory to balagan, passing through Persian to Russian via a Turkic intermediary.