NidÃÂna () is a Sanskrit and Pali word that means "cause, motivation or occasion" depending on the context. The word is derived from the Sanskrit prefix ni- (; "down", "into") plus the root dÃÂ (; "to bind"), forming the verb nidÃÂ (; "to bind on, fasten"). This in turn yields the noun nidÃÂna (; lit. "a band, rope or halter"). It appears in the Rigveda, such as hymn 10.114.2, and other Hindu scriptures, wherein it means "primary or first cause, linked cause"; in other contexts such as Rigveda 6.32.6, nidÃÂna refers to the literal meaning of a rope or band that links, binds or fastens one thing to another, such as a horse to a cart. The word has been borrowed into modern languages such as Hindi and Marathi to mean "diagnosis" or "primary cause" among others.
NidÃÂna is the term used to describe the standard introduction of a Buddhist sutra, where the formula "Thus have I heard" (attributed to ÃÂnanda) is followed by a description of the location in and occasion on which the Buddha gave a particular teaching.
The other primary use of nidÃÂna in the Buddhist tradition is in the context of the Twelve NidÃÂnas, also called the "Twelve Links of Dependent Origination". These links present the mechanistic basis of repeated birth, saá¹ÂsÃÂra, and resultant duḥkha (suffering, pain, unsatisfactoriness) starting from avidyà(ignorance, misconceptions).
The term nidÃÂna appears in numerous ancient and medieval Hindu texts wherein it means "first cause, primary cause, original or essential cause". This includes the Upanishads that include theosophical speculations, as well as medical texts such as Sushruta Samhita and Charaka Samhita, where a large sub-book is titled NidÃÂna SthÃÂna (; "Pathology"), as well as in chapters of the Puranas, wherein these discuss cause of disease or various natural phenomena.