1. Any redistribution in space of the intensity of waves that results from the presence of an object causing variations of either the amplitude or phase of the waves: Diffraction is a phenomenon of all electromagnetic radiation, including radio waves; microwaves; infrared, visible, and ultraviolet light; and X-rays.
2. Etymology: from French diffraction or directly from Modern Latin diffractionem, diffractio, a noun of action from the past participle stem of Latin diffringere, "to break in pieces"; from dis-, "apart" + frangere, "to break".

The change in the directions and intensities of a group of waves of electrons when they pass through crystalline matter: Electron diffraction is useful in the study of the structures of materials.

Electron diffraction refers to the bending of electromagnetic waves as they pass around corners or through holes smaller than the wavelengths of the waves themselves.

The occurrence or the technique of producing electron diffractions through the incidence of electrons on matter.

The bending of an electron stream which occurs when the electron diffraction travels through a medium; such as, very thin metal foil.