The word "glagolitic" is defined as an adjective meaning "of, relating to, or denoting a Slavic alphabet whose invention is attributed to Saint Cyril, preserved only in certain Roman Catholic liturgical books found in Dalmatia" [C19: from New Latin 'glagoliticus', from Serbo-Croat 'glagolica' the Glagolitic alphabet; related to Old Church Slavonic 'glagolŭ' word].
The text is in Old Church Slavonic, with five vocal movements that correspond to the Catholic Ordinary of the Mass, omitting "Dona nobis pacem" in the Agnus Dei. The musical origins of the work can be traced to Janáček's Latin setting of the Kyrie, Agnus Dei, and Credo for organ and chorus. This was used as a dictation exercise by his composition students in 1908.
Janáček had extensive experience working with choirs, as well as writing a large amount of choral music, and this work is his finest in the genre. It begins and closes with triumphant fanfares dominated by the brass. In between these sections lies particularly vibrant and rhythmic writing for solo voices as well as choir. Before the closing Intrada, Janáček introduces a dramatic organ solo of considerable originality – a perpetuo moto of wild energy. Janáček's Glagolitic Mass is considered one of the century's masterworks and is frequently performed and recorded today.
Janáček was a strong supporter of pan-Slavism, and this mass has been viewed as a celebration of Slavic culture.