Dif*frac"tion (?), n. [Cf. F. diffraction.] Opt.
The deflection and decomposition of light in passing by the edges of opaque bodies or through narrow slits, causing the appearance of parallel bands or fringes of prismatic colors, as by the action of a grating of fine lines or bars.
Remarked by Grimaldi (1665), and referred by him to a property of light which he called diffraction.
Whewell.
Diffraction grating. Optics See under Grating. -- Diffraction spectrum. Optics See under Spectrum.
© Webster 1913.