fundamental cause of duhkha, tendency of contrary perception
The first of the five kleshas described by Patanjali (see Patanjali). A false notion of the nature of reality into which all humans are born. Often translated as ignorance but here as Patanjali defines it, not simply intellectual ignorance but mistaking the impermanent for the Permanent, the impure for the pure, the painful for the pleasant and the not-self for the Self.
Sanskrit - "non-(spiritual) knowledge", metaphysical ignorance. An important Vedantic (and general Hindu and Buddhist) concept referring to the deluded state of finite, non-enlightened or non-realised consciousness, according to which one mistakes the imperfect or false understanding of ordinary or limited consciousness for reality. Enlightenment and Liberation mean freedom from avidya, and hence being able to see things as they really are.