homoousian
/ˌhɒməʊˈuːsɪən
/(also homousian)
noun historical
A person who held that God the Father and God the Son are of the same substance. Compare with homoiousian.The arguments between homoiousians and homoousians would be hysterically ridiculous if it weren't for the amount of blood shed over the letter ‘i’.
Origin
Mid 16th century: from ecclesiastical Latin homousianus, from homousius, from Greek homoousios, from homos 'same' + ousia 'essence, substance'.