What is "mazurzenie"

Mazurzenie or mazuration is the replacement or merger of Polish's series of retroflex fricatives and affricates ( written sz, ż, cz, dż) into the alveolar series (written s, z, c, dz). This merger is present in many dialects, but is named for the Masurian dialect.

This phonological feature is observed in dialects of Masuria and Masovia (Masovian dialect), as well as in most of Lesser Poland and parts of Silesia, and on the periphery of Greater Poland (mainly Mazurzy wieleńscy). The boundary of mazurzenie runs from north-east to south-west. It may have originated between the 14th and 16th centuries in the Masovian dialect.

A similar phenomenon, Tsokanye, has been observed in the Old Novgorod dialect of Old East Slavic. It also occurs in a few areas of the Chakavian dialect of Croatian, known as tsakavism. In the Polish and Kashubian dialects there are also other similar phenomena, jabłonkowanie (in the dialects of some Silesian Górale) and kaszubienie (in many variants of Kashubian).