Hallelujah (hălˌəlōˈyə) [key] or Alleluia ăl– [Heb., = praise the Lord], joyful expression used in Hebrew worship; cf. Pss. 104–6, 111–13, 115–17, 135, 146–50. Christian liturgies make wide use of it, particularly at Easter time. The Hallelujah Chorus is the brilliant concluding piece of Part II of Handel's Messiah.