An enneahedron, also called a nonahedron, is a nine-faced polyhedron. The term "enneahedron" is generally preferred over "nonahedron" since while the former combines the Greek words for "nine" (ennea-) and "angle" (-hedron), the latter combines the Latin prefix nona with a Greek suffix.
There are 2606 distinct convex enneahedra, corresponding to the 2606 nonisomorphic nonahedral graphs.
Examples include those illustrated above and summarized in the following table.
 |  |  | name |
| 9 | 15 | 8 | elongated
triangular dipyramid ( ) |
| 9 | 16 | 9 | elongated square pyramid
( ) |
| 9 | 16 | 9 | Goddard-Henning enneahedron |
| 9 | 16 | 9 | octagonal pyramid |
| 9 | 18 | 11 | Herschel enneahedron |
| 9 | 21 | 14 | heptagonal prism |
