Het·er·o·ou·si·an 
(hĕt′ə-rō-sē-ən, -ousē-ən) also Het·er·ou·si·an (hĕt′ə-r-, -rou-)
(hĕt′ə-rō-sē-ən, -ousē-ən) also Het·er·ou·si·an (hĕt′ə-r-, -rou-)n.
A Christian who believes that the substance and nature of God the Father and God the Son are different; an Arian.
[From Greek heteroousios, differing in substance : hetero-, hetero- + ousiā, substance, nature; see HOMOIOUSIAN.]
Het′er·o·ousi·an, Het′er·ousi·an adj.