Hypostatic Union

Hypostasis is the Greek word for a concrete individual subject, a person. The hypostatic union is the Church's name for the way Christ's two natures are joined: not blended into a third thing, not sitting side by side as two persons, but united in the one Person of the eternal Son. The Council of Chalcedon defined that the two natures are united “without confusion, without change, without division, without separation.” So everything Jesus does — sleeping in a boat, raising Lazarus — is done by one divine Person, and Mary, who bore that Person, is rightly called Mother of God.