The Greek form (Rev. 19:1, 3, 4, 6) of the Hebrew Hallelujah = Praise ye Jehovah, which begins or ends several of the psalms (106, 111, 112, 113, etc.).
Easton’s Bible Dictionary
Alleluia
Name meaningpraise the Lord
Easton’s Bible Dictionary (1897), public domain. Text via Theographic Bible Metadata, CC BY-SA 4.0.