Ayzik Zaretski (1891-1956) was a Yiddish linguist, lexicographer and author. Born in Pinsk, he studied mathematics at Derpt University (now Tartu, Estonia) in 1913–17 and published studies on geometric terminology in Yiddish (1923) as well as Yiddish translations of mathematics (1921) and algebra (1924) textbooks. Zaretzki's major contribution, however, was in the field of Yiddish linguistics. After the 1917 Revolution he joined the Jewish Labor Bund and then the Communist Party (1918), which he left in 1921. He was briefly head of the Jewish Department of the People's Commissariat for Education in Moscow (1920). As the central figure in the movement for a reformed Yiddish orthography, Zaretzki wrote a number of books and articles on the subject, which later received government sanction, becoming the official Yiddish orthography of the Soviet Union, one of whose striking characteristics is the abandonment of the traditional spelling of Yiddish words of Hebrew-Aramaic origin. In the early 1930s he advocated introducing the Latin alphabet for Yiddish, but did not find many supporters among his fellow language-planners.

A leading methodologist in Yiddish language teaching, Zaretzki wrote a number of books in this field while pursuing extensive and intensive research into Yiddish grammar, especially syntax, and was noted for his penetrating observations and generalizations. Foremost among his numerous publications in this field is Praktishe Yidishe Gramatik ("Practical Yiddish Grammar," 1926, 1927, rev. ed. 1929 under the title Yidishe Gramatik ("Yiddish Grammar")). From 1928 he taught Yiddish linguistics at the Second Moscow State University, later transformed into the Moscow Teachers' Training Institute. When the Yiddish department was closed (1938), he became a university lecturer of general and Russian linguistics. He died in Kursk, Russia.