Alleluia
Archimandrite Nikifor’s Biblical Encyclopedia
(Rev. 19:1) — a Hebrew word, Hallel, meaning “praise God.” This word was a common exclamation of joy and praise in Hebrew worship; it opens and closes several of the psalms, as for instance Psalms 112–117 [in the Hebrew numbering]. St. John the Theologian, in a solemn heavenly hymn sung by the angel who came down from heaven, after a prophetic depiction of God’s righteous judgment upon Babylon, heard “as it were the voice of a great multitude, and as the voice of many waters, and as the voice of mighty thunderings, saying, Alleluia: for the Lord God omnipotent reigneth” (19:6).
The hymn sung by the Lord together with the apostles after the Last Supper (Matt. 26:30) was, it appears, likewise one of the psalms of praise. This song is still used to this day in the worship of the Christian Church.