Prism (geometry)

Set of uniform n-gonal prisms
Example: uniform hexagonal prism (n = 6)
Type	uniform in the sense of semiregular polyhedron
Faces	2 n-sided regular polygons n squares
Edges	3n
Vertices	2n
Euler char.	2
Vertex configuration	4.4.n
Schläfli symbol	{n}×{ } [1] t{2,n}
Conway notation	Pn
Coxeter diagram
Symmetry group	Dnh, [n,2], (*n22), order 4n
Rotation group	Dn, [n,2]+, (n22), order 2n
Dual polyhedron	convex dual-uniform n-gonal bipyramid
Properties	convex, regular polygon faces, isogonal, translated bases, sides ⊥ bases
Net
Example: net of uniform enneagonal prism (n = 9)

In geometry, a prism is a polyhedron comprising an n-sided polygon base, a second base which is a translated copy (rigidly moved without rotation) of the first, and n other faces, necessarily all parallelograms, joining corresponding sides of the two bases. All cross-sections parallel to the bases are translations of the bases. Prisms are named after their bases, e.g. a prism with a pentagonal base is called a pentagonal prism. Prisms are a subclass of prismatoids.^[2]

Like many basic geometric terms, the word prism (from Greek πρίσμα (prisma) 'something sawed') was first used in Euclid's Elements. Euclid defined the term in Book XI as “a solid figure contained by two opposite, equal and parallel planes, while the rest are parallelograms”. However, this definition has been criticized for not being specific enough in regard to the nature of the bases (a cause of some confusion amongst generations of later geometry writers).^[3][4]