General English


  • Triangular-sectioned glass cylinder which can be used to split light into its spectral components or to recombine it once divided, because of the differential rate at which glass refracts light of different wavelengths. diffraction gratings have largely replaced them in astronomical equipment.



  • A transparent optical material or lens, such as that made of glass, with no less than two polished plane surfaces which are at an angle relative to each other so as to reflect or refract light. A prism may be utilized, for instance, to disperse white light into its component colors, to produce plane-polarized light from unpolarized light, or to invert an image. Used, for instance, in cameras and binoculars. Also called optical prism.

Media Studies

  • noun a device used to bend and concentrate light, used in the workings of some types of camera

Origin & History of “prism”

The etymological idea underlying the word prism is of its shape, that of a ‘sawn-off’ piece. It comes via medieval Latin prisma from Greek prī́sma, a derivative of the verb prī́zein ‘saw’. Its optical application emerged in English at the beginning of the 17th century.