[ ˌhɒmɔɪ'u:sɪən , -'aʊ- , -z- ]
■ noun historical a person who held that God the Father and God the Son are of like but not identical substance. Compare with homoousian .
Origin
C17: via eccles. L. from Gk homoiousios , from homoios 'like' + ousia 'essence, substance'.