Jan Baudouin de Courtenay

Jan Niecisław Ignacy Baudouin de Courtenay, also Ivan Alexandrovich Baudouin de Courtenay (; 13 March 1845 – 3 November 1929) was Polish linguist and Slavist, best known for his theory of the phoneme and phonetic alternations.

For most of his life Baudouin de Courtenay worked at Imperial Russian universities: Kazan (1874–1883), Dorpat (now Estonia) (1883–1893), Kraków (1893–1899) in Austria-Hungary, and St. Petersburg (1900–1918). In 1919–1929 he was a professor at the re-established University of Warsaw in a once again independent Poland. Provided by Wikipedia