Mazuration
Mazuration, also known as mazurzenie (Polish pronunciation: [mazuˈʐɛɲɛ] ) or more rarely sakanie, 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.