noun pl. hypostases -·ses′ (-sēz′)

1. the masking or suppression of a gene by another gene that is not its allele
2. Med.
   1. a deposit or sediment
   2. a settling of blood in the lower parts of the body as a result of a slowing down of the blood flow
3. Philos. the underlying, essential nature of a thing
4. Christian Theol.
   1. the unique nature of the one God
   2. any of the three persons of the Trinity, each person having the divine nature fully and equally
   3. the union of the wholly divine nature and of a wholly human nature in the one person of Jesus Christ
      in full hypostatic union

Etymology: Gr, a supporting, foundation < hyphistanai, to set under, pass, stand under < hypo-, under (see hypo-) + histanai, to stand, cause to stand