Hebrew liturgical expression meaning “praise ye Yah” (“praise the Lord”). It appears in the Hebrew Bible in several psalms, usually at the beginning or end of the psalm or in both places. In ancient Judaism it was probably chanted as an antiphon by the Levite choir. In the New Testament it appears only in Revelation 19, where it occurs four times. It was translated in the Septuagint (Jewish Greek version of the Bible made in the pre-Christian period) and became “alleluia” in the Vulgate (4th-century Christian Latin version). The early Christians adopted the expression in their worship services, and it appeared in Orthodox, Roman Catholic, Anglican, and some Protestant liturgies and in hymns.