Octoechos [Ukrainian: октоїх; oktoikh or осьмогласник; osmohlasnyk], from the Greek for ‘eight’ and ‘voice.’ A liturgical book used in the Eastern Catholic and Orthodox churches. It contains the texts and notes sung by precentors or the faithful for matins, vespers, and the Divine Liturgy. Each week in the liturgical cycle has a specific tone or mode, used to sing the troparion, kondakion or canticle, and other melodies. In total there are eight tones that alternate throughout the year. The first Octoechos was translated from Greek into Church Slavonic by Saint Cyril and Saint Methodius, and the first printed Eastern Slavic Octoechos was published in Cracow in 1491.
[This article originally appeared in the Encyclopedia of Ukraine, vol. 3 (1993).]