Source : Webster's Revised Unabridged Dictionary (1913)

Marcionite \Mar"cion*ite\, n. (Eccl. Hist)
   A follower of Marcion, a Gnostic of the second century, who
   adopted the Oriental notion of the two conflicting
   principles, and imagined that between them there existed a
   third power, neither wholly good nor evil, the Creator of the
   world and of man, and the God of the Jewish dispensation.
   --Brande & C.