Katavasia

In Eastern Orthodox liturgical practice, a Katavasia (Greek: καταβασία, from καταβαίνω, "to descend") refers to the concluding verses (irmos) of each ode of a Canon that are chanted alternately by the choirs standing on opposite sides of the soleas (the area in front of the iconostasis) as they "descend" from their usual places and meet in the center of the church.

Specifically, the Katavasia is the Irmos of a particular ode that is sung after the concluding hymn (Theotokion) of that ode. It serves as a concluding summary and affirmation of the theme presented in that ode. Its placement emphasizes the importance and theological significance of the irmos.

The purpose of the choirs meeting in the center is threefold: to demonstrate unity in faith, to add solemnity to the service, and to provide a dynamic and visually symbolic element to the liturgical action.

Not all canons have a Katavasia sung with each ode. During certain festal seasons, particularly the Twelve Great Feasts and the Paschal season, special canons known as the "Canons of the Feast" are chanted, and the Katavasia are sung at each ode. During the Great Fast, the Great Canon of St. Andrew of Crete is sung, but it does not include Katavasia. On ordinary weekdays, the chanting of the full canon may be abbreviated, potentially affecting the frequency of Katavasia. The selection of which irmos to use as the Katavasia is determined by the liturgical calendar and typikon.