Sākṣī, the witness, is the self considered as the unchanging awareness in which all experience appears. It sees the movements of the mind, the coming and going of waking, dream and sleep, without itself moving. Vedānta teachers point to the witness as a way of turning attention from what is known to the knower.
Sākṣī
The witness: the pure consciousness that observes body, mind and the three states without being affected by them.
Also: Sakshi, the witness