(Hebrew קליפות) Also qliphoth, kliffoth, klippot or kellipot. “The World of Shells.” From קליפה, meaning "peel, shell, rind (cheese), skin, cortex, crust, hull, husk."
In Kabbalah, the term klipoth refers to the inferior worlds, the inferno, hell, or abyss. The Klipoth is so named because the souls who descend into the inferior worlds descend without the connection to their own inner divinity, therefore they are "empty shells."
"Adam was drawn downward after the serpent. He went down to learn of all that is below, meaning that he went down to draw the light of Chochmah to the lower Malchut that is missing like the serpent. As he went down for the purpose of drawing light from above to below, his desires and his ways were drawn after the Klipot. This drawing downward of the light of union is the secret of ‘prohibition of the tree of knowledge.’ Since he intended to draw the light downward, he cleaved immediately to the Klipot, even though he had not yet actually drawn any light. They went down to the serpent and saw the desire of the world. And his ways were swayed to this place of Malchut, which is the secret of eating of the tree of knowledge. Then the serpent was drawn after Adam and his wife. It cleaved onto them with its filth, bringing death to them and all subsequent generations." - Zohar 2:55:287
"“And they sewed fig leaves together” (Genesis / Beresheet 3:7), meaning that they were covered by many layers of Klipot of the mixed multitude [the ego]. This was because they were naked without the Torah [law]. Therefore, they were covered in order not to reveal their nakedness, which is the place [the sexual organs] onto which the klipot cling." - Zohar
Study the Klipoth in 2 Kings 17:27-41.