hemi-icosahedron

== English == === Alternative forms === hemicosahedron === Etymology === From hemi- +‎ icosahedron, referring to the fact that it contains half the faces of a regular icosahedron. === Noun === hemi-icosahedron (plural hemi-icosahedra or hemi-icosahedrons) A polyhedron containing 10 triangular faces, 15 edges, and 6 vertices.