Source : Webster's Revised Unabridged Dictionary (1913)

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.