Avidya (devanāgarī: अविद्या avidyā) is a Sanskrit word commonly translated as "ignorance" or "delusion". In spiritual contexts it refers to a fundamental misunderstanding of the nature of Reality.
In Buddhism it is regarded as the first link in the twelve links of dependent origination.
In Patañjali's Raja Yoga Avidyā is seen as the first cause of affliction, defined as "taking the non-eternal for the eternal, the impure for the pure, evil for good and non-self as self".
In Advaita Vedanta Avidya is also seen as the primary factor for illusion, and is defined as adhyāsa, normally translated as "misapprehension" or "wrong cognition".