ennead

noun2

1. •
   (rare) Any grouping or system containing nine objects.
2. •
   (no longer used) The number nine.

noun1

1. •
   One of the six parts of the writings of the Greek-speaking philosopher Plotinus (c. 204–205 – 270), each containing nine treatises, compiled by his student Porphyry (c. 234 – c. 305).

   • Which Darkness is a fourth Property of the Mosaick Matter, and on which Plotinus insists pretty copiously in this second Ennead, and contends we can have no other notion of it, […] — 1662