Upadhi is a term in Hindu philosophy

Hindu philosophy

Hindu philosophy is divided into six schools of thought, or , which accept the Vedas as supreme revealed scriptures. Three other schools do not accept the Vedas as authoritative...

. An upadhi is external; in Hindu logic

Logic

In philosophy, Logic is the formal systematic study of the principles of valid inference and correct reasoning. Logic is used in most intellectual activities, but is studied primarily in the disciplines of philosophy, mathematics, semantics, and computer science...

, 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

Mind

The concept of mind is understood in many different ways by many different traditions, ranging from panpsychism and animism to traditional and organized religious views, as well as secular and materialist philosophies. Most agree that minds are constituted by conscious experience and intelligent...

 obscuring the true state of man or his self which Indian philosophies seek to remove for the attainment of moksha

Moksha

Within Indian religions, moksha or mukti , literally "release" , is the liberation from samsara and the concomitant suffering involved in being subject to the cycle of repeated death and reincarnation or rebirth.-Origins:It is highly probable that the concept of moksha was first developed in...

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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."