Definition of: diffraction

(di·frak′shən) noun Physics
1. A deviation of rays of light from a straight course when partially cut off by any obstacle or passing near the edges of an opening, or through a minute hole, generally accompanied by prismatic colors due to interference. Diffraction is a phenomenon accompanying all forms of wave motion, its effect being more marked as the wavelength increases. It is best shown by diffraction gratings, plates of glass or polished metal ruled closely with parallel lines, by means of which diffraction spectra are obtained.
2. A similar deviation of sound waves in passing the angle or edge of a large body.