A speech or treatise consisting of nine parts or chapters; any work in nine parts (compare trilogy (3-part), tetralogy (4-part), etc.).
1992, Andrew Lawrence Markus (English quoter), August Pfizmaier (German author), “Über den Text eines japanischen Drama’s†(1870), page 115, quoted in The Willow in Autumn: Ryūtei Tanehiko, 1783-1842, Harvard University Asia Center, ISBN 978-0-674-95351-2, page 76:These works … appear, upon closer scrutiny, to be dramatic, and are actually the seventh and eighth parts of an “ennealogy†(as it were), perhaps “polylogy,†for dramas in Japan frequently are protracted to such lengths.
2011, Ralph Raab, The Tamerlane Trap, iUniverse, page 1Of course, nobody in their right mind would want to commit to an octalogy, ennealogy, or decalogy—or even more!— unless you were a fan of, say, Lemony Snicket