| Type: | Johnson |
| Faces: | 2+3 triangles 3 pentagons |
| Edges: | 15 |
| Vertices: | 9 |
| Dual: | Dual of tridiminished icosahedron (unnamed enneahedron) |
| Properties: | convex |
| Net: | Johnson solid 63 net.png |
In geometry, the tridiminished icosahedron is one of the Johnson solids . The name refers to one way of constructing it, by removing three pentagonal pyramids from a regular icosahedron, which replaces three sets of five triangular faces from the icosahedron with three mutually adjacent pentagonal faces.
The tridiminished icosahedron is the vertex figure of the snub 24-cell, a uniform 4-polytope (4-dimensional polytope).