Adhyāsa is the key concept with which Śaṅkara opens his commentary on the Brahma Sūtras. Ordinary experience, he argues, rests on a mutual superimposition of the self and the not-self: we attribute to the conscious self the qualities of body and mind, and to body and mind the consciousness of the self. Knowledge removes the superimposition, as seeing the rope ends the fear of the snake.
Adhyāsa
Superimposition: the error of attributing to one thing the qualities of another, as when a rope is seen as a snake.
Also: Adhyasa, superimposition