n.; pl. Hypostases [ L., fr. Gr. &unr_; subsistence, substance, fr. &unr_; to stand under; &unr_; under + &unr_; to stand, middle voice of &unr_; to cause to stand. See Hypo-, and Stand. ] 1. That which forms the basis of anything; underlying principle; a concept or mental entity conceived or treated as an existing being or thing. [ 1913 Webster ]

2. (Theol.) 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. [ 1913 Webster ]

☞ The Council of Alexandria (a. d. 362) defined hypostasis as synonymous with person. Schaff-Herzog. [ 1913 Webster ]

3. 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. [ 1913 Webster ]

4. (Med.) That which is deposited at the bottom of a fluid; sediment. [ 1913 Webster ]