The 8th century teacher of Advaita Vedanta, Shankaracharya, noted at the beginning of his commentary on the Brahma Sutras that avidya is synonymous with “superimposition.” For example, an individual might believe they are the body, which, Vedanta would argue, is only a superimposition onto one’s real identity—the Self. Thus, the ultimate definition of avidya, or personal ignorance, is the inability to discriminate between the Self and non-Self.
However, Shankara uses various expressions to signify avidya throughout his work that, when translated from Sanskrit, include: superimposition, erroneous inversion, error, wrong knowledge, wrong cognition, misapprehension, darkness, confusion and delusion.
Avidya is also sometimes used interchangeably with maya as macrocosmic ignorance—that which "shapes" consciousness to give the appearance of the world. However, in general, avidya refers to personal ignorance (microcosmic ignorance) and how the individual superimposes their own conditioning onto reality and thus, misinterprets it.