- a philosophical system, originated in the 3rd century a.d. by Plotinus, founded chiefly on Platonic doctrine and Eastern mysticism, with later influences from Christianity. It holds that all existence consists of emanations from the One with whom the soul may be reunited.
- a philosophical system which was first developed in the 3rd century ad as a synthesis of Platonic, Pythagorean, and Aristotelian elements, and which, although originally opposed to Christianity, later incorporated it. It dominated European thought until the 13th century and re-emerged during the Renaissance
