Upadhi

Upadhi (Sanskrit: "imposition" or "limitation") is a term in Hindu philosophy. An upadhi is external; in Hindu logic, it is an extra limitation or qualification on something. It can also be viewed as a disguise or vehicle for true reality, both defining something and limiting it. For example, the body of a man or animal is the upadhi of its spirit. Upadhi is one of many conditions of body and mind obscuring the true state of man or his self which Indian philosophies seek to remove for the attainment of moksha.

Extract from Helena Blavatsky's Theosophical Glossary:
"Basis; the vehicle, carrier or bearer of something less material than itself: as the human body is the upâdhi of its spirit, ether the upâdhi of light, etc., etc.; a mould; a defining or limiting substance."