What is "homoiousian"

Homoiousian \Ho`moi*ou"si*an\, a. Of or pertaining to Homoiousians, or their belief.

Homoiousian \Ho`moi*ou"si*an\, n. [Gr. ?, ?, of like substance; "o`moios + o'ysi`a the substance, being, essence.] (Eccl. Hist.) One of the semi-Arians of the 4th century, who held that the Son was of like, but not the same, essence or substance with the Father; -- opposed to homoousian.

1680s, from Greek homoiousios "of the same essence," from homos "one and the same" (see homo- (1)) + ousia "essence" (see Parousia).

a. having a similar but not identical essence, especially with reference to the first and second persons of the Trinity n. (context historical English) One of the Semi-Arians of the 4th century who held that the Son was of like, but not the same, essence or substance with the Father.

A homoiousian (from the from , hómoios, "similar" and , ousía, "essence, being") was a member of 4th-century AD theological party which held that God the Son was of a similar, but not identical, substance or essence to God the Father. Proponents of this view included Eustathius of Sebaste and George of Laodicea. Homoiousianism arose in the early period of the Christian religion out of a wing of Arianism. It was an attempt to reconcile the seemingly irreconcilable views of the pro-Nicene homoousians, who believed that God the Father and Jesus his son were identical (, homós) in substance, with the "neo-Arian" position that God the Father is "incomparable" and therefore the Son of God can not be described in any sense as "equal in substance or attributes" but only "like" (, hómoios) the Father in some subordinate sense of the term.

Homoiousia is the theological doctrine that Jesus the Son of God and God the Father are of similar ( homoio- or homeo-) but not the same substance, a position held by the Semi-Arians in the 4th century. It contrasts with the homoousia of orthodox Trinitarianism and the heteroousia of Arianism.