Diffusivity is a term used to describe the property of a substance to move or spread through another substance. Some synonyms for diffusivity include permeability, porosity, dispersion, permeation, scattering, and migration. These terms can also be used in specific fields or contexts. For example, in chemistry, diffusivity can be referred to as molecular mobility. In engineering, diffusivity can be called thermal conductivity or mass transfer. In biology, it is referred to as the diffusion coefficient. Whatever the context, synonyms for diffusivity all describe the ability of a substance to move and spread through its environment.