Slovak_language The Slovak language ('slovenčina , not to be confused with slovenščina), sometimes incorrectly called “Slovakian”, is an Indo-European language that belongs to the West Slavic languages (together with Czech, Polish, Silesian, Kashubian, and Sorbian).The Czech and Slovak languages are mutually intelligible which means that even after the dissolution of Czechoslovakia Czech may be used in all official proceedings and documents in Slovakia, and vice versa.