Source : Webster's Revised Unabridged Dictionary (1913)

Ennead \En"ne*ad\, n. [Gr. ?, ?, fr. ? nine.]
   The number nine or a group of nine.

   {The Enneads}, the title given to the works of the
      philosopher Plotinus, published by his pupil Porphyry; --
      so called because each of the six books into which it is
      divided contains nine chapters.