Material scattering: Of an electromagnetic wave, scattering that is attributable to the intrinsic properties of the material through which the wave is propagating.

Note 1: Ionospheric scattering and Rayleigh scattering are examples of material scattering.

Note 2: In an optical fiber, material scattering is caused by micro-inhomogeneities in the refractive indices of the materials used to fabricate the fiber, including the dopants used to modify the refractive index profile.

Source: from Federal Standard 1037C