diffusion
dif.fu.sion \dif-'yu:-zh*n\ \-'yu:zh-n*l, -*n-*l\ n 1: the action of diffusing or state of being diffused 2: DIFFUSENESS, PROLIXITY 3a: the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement and in dissolved substances move from a region of higher to one of lower concentration 3b1: reflection of light by a rough reflecting surface 3b2: transmission of light through a translucent material 4: the softening of sharp outlines in a photographic image - dif.fu.sion.al aj
Webster's English Dictionary