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.]
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI