Noun
That which forms the basis of anything; underlying principle; a concept or mental entity conceived or treated as an existing being or thing.
Substance; subsistence; essence; person; personality; -- used by the early theologians to denote any one of the three subdivisions of the Godhead, the Father, Son, and Holy Spirit.
Principle; an element; -- used by the alchemists in speaking of salt, sulphur, and mercury, which they considered as the three principles of all material bodies.
That which is deposited at the bottom of a fluid; sediment.
Source: Webster's dictionaryCopts, thus, believe in two natures "human" and "divine" that are united in one hypostasis "without mingling, without confusion, and without alteration". Source: Internet
As expressions and aspects of Creation, Ahura Mazda emanated the Amesha Spentas ("Bounteous Immortals"), that are each the hypostasis and representative of one aspect of that Creation. Source: Internet
From Introduction to Against the Gnostics Plotinus' Enneads as translated by A. H. Armstrong, pp. 220–222: Short statement of the doctrine of the three hypostasis, the One, Intellect and Soul; there cannot be more or fewer than these three. Source: Internet
From the Christological viewpoint, the council adopted hypostasis, i.e. coexisting natures, but its language was less definitive than the 451 Council of Chalcedon. Source: Internet
The Father is the eternal, infinite and uncreated reality, that the Christ and the Holy Spirit are also eternal, infinite and uncreated, in that their origin is not in the ousia of God, but that their origin is in the hypostasis of God called the Father. Source: Internet
Armstrong, pp. 220–2: "Short statement of the doctrine of the three hypostasis, the One, Intellect and Soul; there cannot be more or fewer than these three. Source: Internet