Ah, YHWH(יהוה), that was the one. the kind of "true name" of God (although it still just means The Lord in Hebrew :P) You usually see it romanized as Jehovah, though, since the actual pronunciation is unknown (it became illegal to pronounce this name before Hebrew began writing down vowel sounds). It was typically referred to as "Tetragrammaton" by the greeks, meaning 'four letter word', because they had no way of knowing what it actually sounded like when spoken. To be specific, since around 3bce, only the High Priest of Judaism was allowed to speak it out loud, and even then, only within a tiny box within a certain temple referred to as the Holy of Holies. Since that temple burned down in 70ce, however, there is no longer any circumstance in which it is legal to say the word. When encountering the word in the Torah, Jews will say "Adonai" meaning My Lord, and in other circumstances they will read it as HaShem. When translating the bible to English, it was written as "Lord God" since no transliteration was possible.
