twentyfaced

Twentyfaced is an adjective used to describe an object that has twenty faces, and can also be used as a noun when referring to such an object. In geometry, twenty-faced polyhedra are polyhedra with 20 faces; the most famous example is the regular icosahedron, which has 20 equilateral triangular faces, 12 vertices, and 30 edges. The icosahedron exhibits icosahedral symmetry, and its dual polyhedron is the dodecahedron, with 12 pentagonal faces. Beyond the regular form, many twenty-faced shapes exist, including irregular convex polyhedra and certain non-convex varieties, all classified by their face count.

In gaming, the term frequently appears in reference to the twenty-sided die, or d20, used in tabletop role-playing games. The standard d20 is an icosahedron; when rolled, it yields integers from 1 to 20. Dice are typically made from plastic or resin and numbered on the faces. The geometry of the d20 supports comparatively uniform odds across faces, a feature valued for fair random number generation. Twenty-faced shapes also find use in education and design, illustrating symmetry, polyhedral geometry, and applications in fields such as virology, where icosahedral symmetry is common in certain virus capsids.

See also: Icosahedron, Dodecahedron, Polyhedron, D20 die.