Katabasia

thumb|A Romanian Orthodox [[Horologion opened to the Katabasiae of the Nativity of the Lord.]]

Katabasia or katavasia (Greek καταβασία, from καταβαίον, "descend") is a type of hymn, and the last troparion of an ode of a canon, chanted in the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Byzantine Rite. Its name is derived from the Greek word katabasia for descent, so called because the cantors used to descend from their kliroses (choir stands) and unite in the middle of the church to sing them.