Definition

1. Noun:
   • A Platonic solid: A "regular convex solid" is a three-dimensional geometric shape where all faces are identical regular polygons, and the same number of faces meet at each vertex. These are the only five solids that meet these strict criteria.

Usage

• The term "regular convex solid" is used in geometry to classify and describe the five Platonic solids. It is a formal, academic term.
• Example: "In geometry class, we studied the properties of each regular convex solid."

Examples

• Noun:
  • The cube is a well-known example of a regular convex solid.
  • Plato associated each of the five regular convex solids with a classical element.

Advanced Usage

• "The five regular convex solids": This phrase specifically refers to the complete set: the tetrahedron, cube (hexahedron), octahedron, dodecahedron, and icosahedron.
  • Euclid proved that there are exactly five regular convex solids.

Variants and Related Words

• Platonic solid (n): A direct synonym for a regular convex solid.
  • The dodecahedron is a Platonic solid with twelve pentagonal faces.
• Regular polyhedron (n): Another equivalent term.
  • A regular polyhedron must have congruent faces and vertices.

Synonyms

• Platonic solid
• Regular polyhedron
• Cosmic figure (a historical/poetic term)

Related Phrases

• "The Platonic solids": The most common collective name for the five regular convex solids.
  • The symmetry of the Platonic solids fascinates mathematicians.

Noun

1. any one of five solids whose faces are congruent regular polygons and whose polyhedral angles are all congruent