prism

Short definition from Wiktionary

Noun

1. 1
   A polyhedron with parallel ends of the same polygonal shape and size, the other faces being parallelogram-shaped sides: An object having the shape of a geometrical prism (sense 1).
2. 2
   A polyhedron with parallel ends of the same polygonal shape and size, the other faces being parallelogram-shaped sides: A cutting (“open passage at a level lower than the surrounding terrain, dug for a canal, railway, or road to go through”) or an embankment shaped like a prism (sense 1) or a number of prisms, such that its volume can be easily calculated.
3. 3
   A polyhedron with parallel ends of the same polygonal shape and size, the other faces being parallelogram-shaped sides: A crystal in which the faces are parallel to the vertical axis.
4. 4
   A polyhedron with parallel ends of the same polygonal shape and size, the other faces being parallelogram-shaped sides: A transparent block in the shape of a prism (sense 1), typically with triangular ends, used to reflect or refract light.
5. 5
   A transparent block in the shape of a prism (sense 1), typically with triangular ends, used to reflect or refract light: A spectrum produced by light being refracted through a prism.
6. 6
   A retroreflector (“device which reflects light back to its source with minimal scattering”) which is usually attached to a surveying pole as a target for a total station which emits a light beam at the device and calculates how long it takes to be reflected back in order to measure distance.
7. 7
   A perspective that colours one's perception.