nounEtymology: Late Greek homoousios of the same substance, from Greek hom- + ousia substance — more at homoiousianDate: 1565 an adherent of an ecclesiastical party of the fourth century holding to the doctrine of the Nicene Creed that the Son is of the same substance with the Father
n. (also homousian) hist. a person who held that God the Father and God the Son are of the same substance (cf. HOMOIOUSIAN). Etymology: eccl.L homoousianus f. LL homousius f. Gk homoousios (as HOMO-, ousia essence)
Homoousian Ho`mo*ou"si*an, n. [Gr. ?; ? the same + ? being, essence, substance.] (Eccl. Hist.) One of those, in the 4th century, who accepted the Nicene creed, and maintained that the Son had the same essence or substance with the Father; -- opposed to homoiousian.