But the more fashionable saints of the Arian times, the intrepid Athanasius, the learned Gregory Nazianzen, and the other pillars of the church, who supported with ability and success the Nicene doctrine, appeared to consider the expression of substance as if it had been synonymous with that of nature; and they ventured to illustrate their meaning, by affirming that three men, as they belong to the same common species, are consubstantial, or homoousian to each other.
Source: wiktionary