Linguistically speaking, Czech is – as are Slovak, Polish and the now nearly extinct Lusatian (Wendish) – a Western Slavonic language. Eastern Slavonic languages, such as Russian and Ukrainian, or members of the South Slavonic branch, as Serbian and Croatian, all belong to the same linguistic family. But because Czech, thanks In part to the unique vowel mutation it has undergone, is the most distinctive of all the Slavonic languages, its spoken version can be hard to understand even for other Slav peoples, bar the Slovaks.