Deflection of the rays of light from a straight line in passing by the edge of an opaque body or in passing an obstacle of about the size of the wavelength of the light. [L. dif- fringo, pp. -fractus, to break in pieces]
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dif·frac·tion dif-'rak-shən n a modification which light undergoes in passing by the edges of opaque bodies or through narrow slits or in being reflected from ruled surfaces and in which the rays appear to be deflected and to produce fringes of parallel light and dark or colored bands also a similar modification of other waves (as sound waves)
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dif·frac·tion (dĭ-frakґshən) [dis-1 + L. frangere to break] the bending of waves around small obstacles and the spreading out of waves past openings that are small compared to the wavelengths. See also under grating.Medical dictionary. 2011.