nonet

noun3

1. •
   A group of nine nuclear or subatomic particles.
2. •
   A composition for nine instruments or nine voices.

   • The small-group sides are the best, with the nonet in particular coming through as a sparkling unit that deserves an LP to itself. — 1955
3. •
   A byte of nine bits.

   • The 9-bit nonet is a much more sensible representation. — 2005