The English phonetization of the Hebrew word for God. This word is called the tetragrammaton in Greek. There are no letters for vowel sounds in Hebrew, and at some point the ancient Jews interpreted the commandment to "not take the Lord's name in vain" to mean not to speak the name basically at all (to this day, Orthodox Jews will write G-d instead of God and ' instead of Adonai {Lord in Hebrew}). Thus, no one is really sure how the name was pronounced. It could be "Yahoo-wahoo".