Mazurzenie (Polish pronunciation: [mazuˈʐɛɲɛ] (listen)) or mazuration is the replacement or merger of Polish's series of postalveolar fricatives and affricates /ʂ, ʐ, t͡ʂ, d͡ʐ/ (written ⟨sz, ż, cz, dż⟩) into the dentialveolar series /s, z, t͡s, d͡z/ (written ⟨s, z, c, dz⟩). This merger is present in many dialects, but is named for the Masovian 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. There are also some peripheral mazurating islands in Greater Poland. 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.
The feature is linked to the process of depalatalization (reducing of the number of palatalized consonants) similar to the phenomena of jabłonkowanie and kaszubienie in other dialects.
A rarer term for mazuration is sakanie.
In this article terms such as "non-mazurating", "without mazuration" are taken to refer to dialects which have a three way distinction among sibilants, as does Standard Polish. Technically dialects with e.g. jabłonkowanie also do not mazurate, but for the sake of simplicity this will not be discussed in the article.