What is tetragammatron?

What is the name of the Word which has no vowel and letter y?

The "word" you are asking about is called the Tetragammatron (sp?) In the Hebrew Old Testament, scribes would not spell out the name of God, instead opting to use what translates into English as "YHWH". Modern day translators have added "a" and "e" to the letters to give us "Yahweh" as the Hebrew name of God. This is also translated as "Jehovah". Of course, scripture gives us many names for God including mighty, love, counselor, Prince of peace to name a few.