prism Meaning, Definition & Usage

  1. noun a polyhedron with two congruent and parallel faces (the bases) and whose lateral faces are parallelograms
  2. noun optical device having a triangular shape and made of glass or quartz; used to deviate a beam or invert an image
    optical prism.

WordNet

Prism noun
Etymology
L. prisma, Gr. , fr. , , to saw: cf. F. prisme.
Definitions
  1. (Geom.) A solid whose bases or ends are any similar, equal, and parallel plane figures, and whose sides are parallelograms. ✍ Prisms of different forms are often named from the figure of their bases; as, a triangular prism, a quadrangular prism, a rhombic prism, etc.
  2. (Opt.) A transparent body, with usually three rectangular plane faces or sides, and two equal and parallel triangular ends or bases; -- used in experiments on refraction, dispersion, etc.
  3. (Crystallog.) A form the planes of which are parallel to the vertical axis. See Form, n., 13.

Webster 1913