Knaanic is a tentative name for a number of West Slavic dialects or registers formerly spoken by the Jews in the lands of the Western Slavs, notably the Czech lands, but also the lands of modern Poland, Lusatia, and other Sorbian regions. They became extinct in the Late Middle Ages. Very little is known about their difference from the surrounding Slavic languages. The largest number of samples of Knaanic written in Hebrew script are in Czech; therefore, most commonly Knaanic is associated with Old Czech.

The West Slavic languages are a subdivision of the Slavic language group. They include Polish, Czech, Slovak, Kashubian, Upper Sorbian and Lower Sorbian. The languages have traditionally been spoken across a mostly continuous region encompassing the Czech Republic, Slovakia, Poland, the westernmost regions of Ukraine and Belarus, and a bit of eastern Lithuania. In addition, there are several language islands such as the Sorbian areas in Lusatia in Germany, and Slovak areas in Hungary and elsewhere.