Max Weinreich (Yiddish: מאַקס ווײַנרײַך[2] Maks Vaynraych; Russian: Мейер Лазаревич Вайнрайх, Meyer Lazarevich Vaynraykh; 22 April 1894 – 29 January 1969) was a Russian-American-Jewish linguist, specializing in sociolinguistics[3] and Yiddish, and the father of the linguist Uriel Weinreich, who, a sociolinguistic innovator, edited the Modern Yiddish-English English-Yiddish Dictionary.
In 1923, under the direction of German linguist Ferdinand Wrede [de] in Marburg,[6] he completed his dissertation, entitled "Studien zur Geschichte und dialektischen Gliederung der jiddischen Sprache" (Studies in the History and Dialect Distribution of the Yiddish language).
[7] Remembered as the guiding force of the institute, Weinreich directed its linguistic, or philological section in the period before the Second World War.
Regina returned to Vilnius, but Max and Uriel stayed abroad, moving to New York City in March 1940.
Weinreich is often cited as the author of a witty quip[11][12][13] distinguishing between languages and dialects: "A language is a dialect with an army and navy" ("אַ שפּראַך איז אַ דיאַלעקט מיט אַן אַרמײ און פֿלאָט", "a shprakh iz a dialekt mit an armey un flot"), but he was then explicitly quoting an unknown auditor at one of his lectures at Columbia University shortly after the war in 1945.