s as z.

A spreading or flowing of a liquid substance or fluid, in a lateral as well as a lineal direction; as the diffusion of water; the diffusion of air or light.

A spreading or scattering; dispersion; as a diffusion of dust or of seeds.

A spreading; extension; propagation; as the diffusion of knowledge, or of good principles.

Copiousness; exuberance, as of style.