Definition

1. Noun:
   • A polyhedron with twenty faces: An "icosahedron" is a three-dimensional geometric solid that has exactly twenty flat, polygonal faces. The faces are typically triangles, and the most common form is the regular icosahedron, where all faces are identical equilateral triangles.

Usage Examples

• Noun:
  • In geometry class, we constructed a model of a regular icosahedron.
  • The virus's protein coat often has the shape of an icosahedron.
  • The artist's sculpture was based on the complex form of an icosahedron.

Advanced Usage

• "Regular icosahedron": A specific type of icosahedron that is one of the five Platonic solids. It has 20 equilateral triangular faces, 12 vertices, and 30 edges, and is highly symmetrical.
  • The regular icosahedron is often used to represent the element of water in classical philosophy.

Variants and Related Words

• Icosahedral (adj): Having the form of or relating to an icosahedron.
  • The virus exhibits an icosahedral capsid structure.

Synonyms

• Twenty-faced solid: A descriptive synonym for an icosahedron.
• Polyhedron: The general category of three-dimensional shapes with flat faces, of which an icosahedron is a specific type.

Noun

1. any polyhedron having twenty plane faces