Definition of "icosahedron" [i•co•sa•he•dron]

• A polyhedron having 20 faces. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The icosahedron is another of the five regular, or Platonic, bodies having all their sides, angles, and planes similar and equal."
• "Then, about 10 years ago, the mathematician Reidun Twarock developed a more general theory of the geometry of viruses based on the symmetries of the icosahedron, but using shapes in six dimensions, not three."
• "I've rolled the icosahedron and painted a few miniatures myself so it only raises my charisma to be accepted by that culture."