Yiddish (ייִדיש, יידיש or אידיש, yidish/idish, pronounced [ˈ(j)ɪdɪʃ], lit. "Jewish"; in older sources ייִדיש-טײַטש Yidish-Taitsh, lit. Judaeo-German) is the historical language of the Ashkenazi Jews. It originated during the 9th century in Central Europe, providing the nascent Ashkenazi community with a High German-based vernacular fused with elements taken from Hebrew and Aramaic as well as from Slavic languages and traces of Romance languages. Yiddish writing uses the Hebrew alphabet.
The earliest surviving references date from the 12th century and call the language לשון־אַשכּנז (loshn-ashknaz, "language of Ashkenaz") or טײַטש (taytsh), a variant of tiutsch, the contemporary name for Middle High German. Colloquially, the language is sometimes called מאַמע־לשון (mame-loshn, lit. "mother tongue"), distinguishing it from לשון־קודש (loshn koydesh, "holy tongue"), meaning Hebrew and Aramaic. The term "Yiddish", short for Yidish Taitsh ("Jewish German"), did not become the most frequently used designation in the literature until the 18th century. In the late 19th and into the 20th century the language was more commonly called "Jewish", especially in non-Jewish contexts,[clarification needed] but "Yiddish" is again the more common designation today.
Modern Yiddish has two major forms. Eastern Yiddish is far more common today. It includes Southeastern (Ukrainian–Romanian), Mideastern (Polish–Galician–Eastern Hungarian), and Northeastern (Lithuanian–Belarusian) dialects. Eastern Yiddish differs from Western both by its far greater size and by the extensive inclusion of words of Slavic origin. Western Yiddish is divided into Southwestern (Swiss–Alsatian–Southern German), Midwestern (Central German), and Northwestern (Netherlandic–Northern German) dialects. Yiddish is used in a number of Haredi Jewish communities worldwide; it is the first language of the home, school, and in many social settings among many Haredi Jews, and is used in most Hasidic and some Lithuanian yeshivas.
The term "Yiddish" is also used in the adjectival sense, synonymously with "Jewish", to designate attributes of Yiddishkeit ("Ashkenazi culture"; for example, Yiddish cooking and "Yiddish music" - klezmer).
Prior to the Holocaust, there were 11–13 million speakers of Yiddish among 17 million Jews worldwide. 85% of the approximately 6 million Jews who died in the Holocaust were Yiddish speakers, leading to a massive decline in the use of the language. Assimilation following World War II and aliyah, immigration to Israel, further decreased the use of Yiddish both among survivors and among Yiddish-speakers from other countries (such as in the Americas). However, the number of speakers is increasing in Hasidic communities.
(Courtesy of Yiddish Language Wikipedia)