This is from Encarta dictionary.
hallelujah or halleluiah or alleluia
Definition:
1. used to express praise to God: used to express praise or thanks to God
2. used to express relief: used to express relief, welcome, or gratitude.
By the way Razza I'd have thought it would be quite hard to look something up in a dictionary if you cant spell it in the first place. (Tongue in cheek)