The word ????????>? occurs in the LXX, answering to the Hebrew word halal in the Psalms translated 'praise ye the Lord.' It is an ascription of praise to God. In Re 19:1,3-4,6 the praise is heard in heaven: through mercy the saint learns to raise his Hallelujah on his way thither.
After these things I heard as it were a loud voice of a great multitude in heaven, saying, Hallelujah I The salvation, and the glory, and the power, belong to our God;
And a second time they said, Hallelujah! and her smoke goeth up for ever and ever. And the twentyfour elders and the four living creatures fell down and worshipped God that sat on the throne, saying, Amen, hallelujah!
And I heard as it were the voice of a great multitude, and as the voice of many waters, and as the voice of mighty thunders, saying, Hallelujah! for the Lord our God the Almighty reigneth.