con·sub·stan·tial / ˌkänsəbˈstanchəl/ • adj. of the same substance or essence (used esp. of the three persons of the Trinity in Christian theology): Christ is consubstantial with the Father.DERIVATIVES: con·sub·stan·ti·al·i·ty / -ˌstanchēˈalətē/ n.

Consubstantial. Of one and the same substance, hence also being. In Christian use the word refers especially to the relationship among the persons of the Trinity. The Lat. consubstantialis is the Western counterpart of Gk. homoousios, the test-word of anti-Arian orthodoxy.