A fusion language based grammatically in Middle-High German, but with significant admixture from Hebrew, Aramaic, Slavic, and other languages. Yiddish is considered to have become a Jewish vernacular as early as the 9th century. As the Jews spread across Central and Eastern Europe, Yiddish went with them, evolving with each new settlement.

Just prior to WWII, it was the most widely spoken Jewish language, with approximately 11 million speakers, a figure that made up about 75% of all Jews worldwide. Because most of the six million Jews who were murdered in the Holocaust were Yiddish speakers, numbers of those who spoke the language declined significantly. This decline, combined with linguistic assimilation in North America, the USSR, and Israel, resulted in a waning of usage and the serious decline of the Yiddish press and theater, which had once been significant. While currently thought to be a “dying” language, its use has actually seen growth in recent years. This is due to the growth of Hasidim and other Haredim, whose birthrates and use of Yiddish as a vernacular has increased the number of contemporary speakers to around 600,000.

Although it is a language like all others, Yiddish terminology is popularly referenced for its humor and clever idiomatic expressions.