(Christianity) An early Christian following akin to but distinct from gnosticism which rejected the validity of the Old Testament and essentially denied the Trinity, regarding God the Father as an inferior demiurge, and that Jesus had nothing to do with the First Person of the Trinity.

A diminutive of the male given name Marcus, from Latin or Ancient Greek, variant of Marc or Mark, equivalent to Koine Greek Μᾱρκίων (Mārkíōn) or Latin Mārciōn