Certain jazz combo

• Biggish combo
• Composition for nine voices
• The Muses, for example
• Louis Spohr chamber work
• Group on Miles Davis's "Birth of the Cool," e.g.
• Hydra's heads, e.g
• A chamber work by Louis Spohr was the first to bear this title
• Medium-sized jazz combo
• Music for nine parts

Wiktionary Word definitions in Wiktionary
n. 1 (context music English) a composition written for nine instruments or nine voices 2 a group of nine nuclear or subatomic particles 3 (context computing English) A byte of nine bits.