PRISM

noun Etymology: Late Latin ~at-, ~a, from Greek, literally, anything sawn, from priein to saw Date: 1570 a polyhedron with two polygonal faces lying in parallel planes and with the other faces parallelograms, 2. a transparent body that is bounded in part by two nonparallel plane faces and is used to refract or disperse a beam of light, a ~-shaped decorative glass luster, a crystal form whose faces are parallel to one axis, a medium that distorts, slants, or colors whatever is viewed through it