Webster's Revised Unabridged Dictionary · 1913

Homoousian

Homoousian , noun

[Greek {not transcribed}; {not transcribed} the same + {not transcribed} being, essence, substance.]

(Ecclesiastical 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.

Homoousian , adjective

Of or pertaining to the Homoousians, or to the doctrines they held.