What does icosahedral mean?
Icosahedral is an adjective describing something shaped like, structured as, or exhibiting the symmetry of an icosahedron. An icosahedron is a polyhedron made from 20 triangular faces, with five triangles meeting at each vertex. The term is especially useful in geometry and the physical sciences, where it describes symmetrical forms in crystals, molecules, and viruses. In virology, an icosahedral capsid resembles a small icosahedron, with protein subunits arranged with approximate rotational symmetry. Architects and designers may also use icosahedral structures to create visually complex frameworks based on interconnected triangles. Outside technical contexts, the word is uncommon, but it provides a precise way to name a distinctive three-dimensional form and the mathematical symmetry associated with it.
adjectiveRelating to or shaped like an icosahedron, a polyhedron with 20 triangular faces. It also describes objects or structures with icosahedral symmetry.
- Having the shape, structure, or symmetry of an icosahedron.
"The molecule has an almost perfect icosahedral structure."
"The virus is approximately icosahedral, with protein capsomers arranged around its genetic material."
"The architect used icosahedral forms to create a network of triangular surfaces."
Twenty triangular faces meet at each vertex of an icosahedron, creating one of geometry’s most symmetrical forms.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does icosahedral come from?
The word combines the Greek eikosi, meaning “twenty,” with the geometric element hedra, meaning “face” or “seat,” and the adjective suffix -al. The resulting terminology distinguishes a solid with 20 triangular faces from related polyhedra whose names indicate other numbers of faces. The form is a development of the established English noun icosahedron and follows the standard English adjective pattern -oid to -oidal.
Related word forms
How icosahedral is actually used
This is a specialized term used mainly in geometry, chemistry, crystallography, architecture, and virology. It is uncommon in ordinary conversation.
Easily confused with icosahedral
An icosahedron is the three-dimensional solid with 20 triangular faces, whereas icosahedral is the adjective describing that shape or its symmetry.