(initial capital letter) a group of nine related deities, including Osiris, Isis, and Set, whose lineage and functions were arranged and explained by the theologians of Heliopolis.
b.
any group of deities arranged in a similar way, often more or less than nine in number.
Origin: 1645–55; < Gk ennead- (s. of enneás), equiv. to enné(a) nine+ -ad--ad1
"group of nine things," 1653, from Gk. enneas (gen. enneados) "group of nine," from ennea "nine" (cognate with Skt. nava, L. novem, Goth. niun, O.E. nigun; see nine).