Church Slavonic, also known as Church Slavic, New Church Slavonic, New Church Slavic or just Slavonic (as it was called by its native speakers), is the conservative Slavic liturgical language used by the Eastern Orthodox Church in Belarus, Bosnia and Herzegovina, Bulgaria, North Macedonia, Montenegro, Poland, Ukraine, Russia, Serbia, the Czech Republic and Slovakia, Slovenia and Croatia. The language appears also in the services of the Russian Orthodox Church Outside of Russia, the American Carpatho-Russian Orthodox Diocese, and occasionally in the services of the Orthodox Church in America. In addition, Church Slavonic is used by some churches which consider themselves Orthodox but are not in communion with the Orthodox Church, such as the Montenegrin Orthodox Church and the Russian True Orthodox Church. The Russian Old Believers and the Co-Believers also use Church Slavonic. Church Slavonic is also used by Greek Catholic Churches in Slavic countries, for example the Croatian, Slovak and Ruthenian Greek Catholics, as well as by the Roman Catholic Church (Croatian and Czech recensions). In the past, Church Slavonic was also used by the Orthodox Churches in the Romanian lands until the late 17th and early 18th centuries, as well as by Roman Catholic Croats in the Early Middle Ages. Source: Wikipedia (en)