diffusion
n.
late 14c., from Latin diffusionem (nominative diffusio) "a pouring forth," noun of action from past participle stem of diffundere "scatter, pour out," from dis- "apart, in every direction" (see dis-) + fundere "pour" (see found, v.2).
〔蒋〕[fus=pour灌，流，倾泻，-ion名词后缀] 散开，扩散，弥漫，传布