Enneadecahedron

Octadecagonal (18-sided) pyramid

A enneadecahedron (or enneakaidecahedron) is a polyhedron with 19 faces. No enneadecahedron is regular; hence, the name is ambiguous.

There are numerous topologically distinct forms of an enneadecahedron, for example the octadecagonal (18-sided) pyramid, or the heptadecagonal (17-sided) prism; the latter is the only convex enneadecahedron with all regular polygonal faces.

Convex enneadecahedra

There are many topologically distinct convex enneadecahedra, excluding mirror images, having at least 12 vertices.^[1] (Two polyhedra are "topologically distinct" if they have intrinsically different arrangements of faces and vertices, such that it is impossible to distort one into the other simply by changing the lengths of edges or the angles between edges or faces.)

References

↑ Counting polyhedra

External links

What Are Polyhedra?, with Greek Numerical Prefixes

Polyhedra

Listed by number of faces

1–10 faces	Monohedron Dihedron Trihedron Tetrahedron Pentahedron Hexahedron Heptahedron Octahedron Enneahedron Decahedron

11–20 faces	Hendecahedron Dodecahedron Tridecahedron Tetradecahedron Pentadecahedron Hexadecahedron Heptadecahedron Octadecahedron Enneadecahedron Icosahedron

Others	Triacontahedron Hexecontahedron Enneacontahedron Apeirohedron

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