dispersion
dis.per.sion \dis-'p*r-zh*n, -sh*n\ n cap 1: DIASPORA 2: the act or process of dispersing : the state of being dispersed 3: the scattering of the values of a frequency distribution from an average 4: the separation of light into colors by refraction or diffraction with fo rmation of a spectrum; also : the separation of nonhomogeneous radiation into components in accordance with some characteristic (as energy) 5a: a dispersed substance 5b: a system consisting of a dispersed substance and the medium in which it is dispersed
Webster's English Dictionary