The West Slavic languages are a subdivision of the Slavic language group that includes Czech, Polish, Slovak, Kashubian, Silesian and Sorbian.
Distinctive features 
Some distinctive features of the West Slavic languages, as from when they split from the East Slavic and South Slavic branches around the 3rd to 6th centuries AD, are as follows:
- development of proto-Slavic tj, dj into palatalized ts, (d)z, as in modern Polish/Czech noc ("night"; compare Russian ночь);
- retention of the groups kv, gv as in Polish gwiazda ("star"; compare Russian звезда; but note also Russian цвет vs. Ukrainian квіт, "flower");
- retention of tl, dl, as in Polish/Czech radlo/rádlo ("ard"; compare Russian рало);
- palatized h developed into š, as in Polish musze (locative case of mucha, "fly");
- the groups pj, bj, mj, vj developed into (soft) consonant forms without the epenthesis of l, as in Polish kupię ("I shall buy"; compare Russian куплю);
- a tendency towards fixed stress (on the first or penultimate syllable);
- use of the endings -ego, -emu for the genitive and dative singular of the adjectival declension;
- use of the pronoun form tъnъ rather than tъ, leading to Polish/Czech ten ("this" (masc.); compare Russian тот);
- extension of the genitive form čьso to nominative and accusative in place of čь(to), leading to Polish/Czech co ("what", compare Russian что).
See also 
- ^ Zenon Klemensiewicz, Historia języka polskiego, 7th edition, Wydawnictwo naukowe PWN, Warsaw 1999. ISBN 83-01-12760-0