Dictionary:

consubstantial

  (kŏn'səb-stăn'shəl)

Of the same substance, nature, or essence.

[Middle English consubstancial, from Late Latin cōnsubstantiālis : Latin com-, com- + Late Latin substantiālis, substantial; see substantial.]

Of one and the same substance. A concept especially necessary in Christian theology, as providing the unity between the three persons in the Trinity. See athanasius, homoousion.

The adjective has one meaning:

Meaning #1: (Christian theology) regarded as the same in substance or essence (as of the three persons of the Trinity)
  Pertains to noun: consubstantiation (meaning #1)