The property by which a being exists of and from itself - self-existence. This is a property belonging to God alone.

Self-existence; the attribute of God in which He exists in and of Himself, independent from anything else.

Aseity is a theological term, a characteristic of being self-derived in contrast to being derived from or dependent on another, hence (apriori) predicable only of God in classical theology. Ideally, this term means that God necessarily exists as opposed to it happens to be the case that God exists. Karl Barth interprets aseity as the freedom of God.