Definition of prism in US English:



  • 1A solid geometric figure whose two end faces are similar, equal, and parallel rectilinear figures, and whose sides are parallelograms.

    • ‘We will show that the area of this ring is equal to the area of the corresponding cross section of the dome, which implies that the dome and the punctured prism have equal volumes.’
    • ‘Volumes of solids such as prisms, pyramids, tetrahedrons, wedges, cylinders and truncated cones are calculated.’
    • ‘He goes on to consider solid geometry giving results on prisms, cylinders, and spheres.’
    • ‘You can readily extend the same approach to other polyhedra, such as prisms and antiprisms.’
    • ‘Ancient stonecutters could thus cleave it perpendicular to the crystal axis to produce hexagonal prisms of any desired length.’
    1. 1.1Optics A glass or other transparent object in prism form, especially one that is triangular with refracting surfaces at an acute angle with each other and that separates white light into a spectrum of colors.
      • ‘By the use of two mirrors, the fluorescence excitation light of 295-nm wavelength was directed perpendicular onto one of the smallest sides of the quartz prism.’
      • ‘According to Blondlot, a narrow stream of N-rays was refracted through the prism and produced a spectrum on a field.’
      • ‘In their experiments, Descartes, Robert Hooke and Edward Boyle had put a screen close to the other side of the prism and seen that the spot of light came out as a mixture of colour.’
      • ‘When he passed a thin beam of sunlight through a glass prism Newton noted the spectrum of colours that was formed.’
      • ‘Newton applied the Method of Analysis to induce the explanatory principle that sunlight comprises rays of differing colours, and that each colour is refracted by the prism through a characteristic angle.’
    2. 1.2figurative Used figuratively with reference to the clarification or distortion afforded by a particular viewpoint.
      ‘they were forced to imagine the disaster through the prism of television’
      • ‘From our side of the prism, each and every one of these events is disparate.’
      • ‘Viewed through the Upper West Side prism in which ‘enlightened’ equals ‘liberal,’ there is some truth to this contention.’
      • ‘It is most certainly distorted by the prism of your own arrogance and ignorance.’
      • ‘So information about her youth is inevitably scarce, apart from her own memoirs, which are bound to be somewhat distorted through the prism of time.’
      • ‘It's a good rule of thumb because seeing a given action through the prism of someone whose motives you are inclined to view favorably is a good check on unwarranted suspicions.’


Late 16th century: via late Latin from Greek prisma ‘thing sawn’, from prizein ‘to saw’.