1. The ninth Sephirah of the cabalistic Tree of Life, the third Sephirah on the Middle Pillar. The term is a Hebrew word meaning "Foundation." It represents the archetype of the number 9, the manifesting aspect of the Godhead. It corresponds to the divine name Shaddai El Chai, the archangel Gabriel, the angelic choir called Kerubim, and Lebanah, or heavenly Sphere of the Moon.
2. The beams of Chesed and Geburah meet in Yesod and thence ariseth in Yesod a brilliant deep violet-purple or puce, and thus is the third Triad completed. And the sphere of its operation is that of Levanah, the Lunar beam, bestowing change, increase and decrease upon created things and it ruleth the Sphere of Action of the Moon and the nature of mankind. And Shaddai is a God who sheddeth benefits, Omnipotent and Satisfying, and Al Chai is the God of Life, the Living One. Its Archangel is Gabriel the Prince of Change and Alteration. And the name of the Order of Angels is Kerubim or Kerubic ones who are also called the Order of Angels.