American Dictionary of the English Language

DIFFUSION, noun S as z.

1. 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.

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

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

4. Copiousness; exuberance, as of style. [Little Used.]