Hȳ-pŏs'ta-sĭs, n.

n.; pl. HȲ-POS'-TA-SEṢ (hȳ-, or hȳ-). [Gr. ὑπόστασις, subsistence, substance, from ὑφίστασθαι, to stand under, from ὑπό, under, and ἱστάσθαι, to stand; Lat. hypostasis, Fr. hypostase, Sp. hipostasis, It. ipostasi.]

1. Substance, or subsistence; hence, used by Greek theologians to denote especially each of the three subdivisions of the Godhead, the Father, Son, and Holy Spirit, which are called by the Latins personæ, whence the modern term persons applied to the Godhead.
2. 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.
3. (Med.) That which is deposited at the bottom of a fluid; sediment.