Definitions for "Homoousios"
Greek for 'same substance', referring to the believe that Jesus and God of the same substance.
Greek word translated as "same in nature." Athanasius advocated its use and the Council of Nicea adopted this word to describe the relationship of Jesus to God although some opposed it because of its earlier use by the Sabellians. Thus, it began as a Oneness word, but was adopted by the trinitarians.