The Taittirīya Upaniṣad describes the person as five sheaths, each subtler than the last: the sheath made of food, of vital breath, of mind, of understanding and of bliss. Vedānta uses the scheme for discrimination: each sheath is examined and found not to be the self, which is the witness of all five.
Pañca-kośa
The five sheaths of the self in the Taittirīya Upaniṣad: of food, breath, mind, understanding and bliss.
Also: Pancha kosha, the five sheaths