four meditations on formlessness
四無色定・四空定・四空処定 (Jpn shi-mushiki-jo, shi-ku-jo, or shi-kusho-jo )
Four levels of meditation leading to the four realms of the world of formlessness.
They are intended to enable one to gain release from the bonds and limitations of matter and deliverance from all thought of matter.
The four realms of the world of formlessness are, in ascending order of quality,
the Realm of Boundless Empty Space,
the Realm of Boundless Consciousness,
the Realm of Nothingness, and
the Realm of Neither Thought Nor No Thought.
By practicing the four meditations on formlessness, one can be reborn among these four realms.
The deeper the meditation, the higher the realm one attains upon rebirth. The four levels of meditation are named for their four corresponding realms.
The first meditation, which leads to rebirth in the Realm of Boundless Empty Space, is called meditation on the Realm of Boundless Empty Space,
the second meditation is called meditation on the Realm of Boundless Consciousness, and so on.
The four realms of the world of formlessness are often interpreted as the levels of awareness that these four meditations enable their practitioners to attain.