Definition of Kevala kumbhaka: absence of inhalation, exhalation, and forced retention. Breathing is suspended spontaneously.

“By itself” (svayaṃ) — it is not produced by will or technique. It is the natural result of the flow of prāṇa in suṣumnā.

When kevala is established, the yogi is in deep meditation. It is the state of respiratory samādhi, gateway to liberation.