Ein Sof, “without end”, is the kabbalists’ name for God in himself, beyond any attribute or name, unknowable even to the highest intellect. From Ein Sof emanate the ten sefirot, through which God becomes manifest. The concept parallels the One of Neoplatonism and the Godhead of Eckhart.
Ein Sof
The Infinite: in Kabbalah, God as utterly hidden and beyond all description, prior to the sefirot.
Also: Ein Sof, the Infinite