Diffusion \Dif*fu"sion\, n. [L. diffusio: cf. F. diffusion.]

1. The act of diffusing, or the state of being diffused; a spreading; extension; dissemination; circulation; dispersion.

A diffusion of knowledge which has undermined superstition. --Burke.

2. (Physiol.) The act of passing by osmosis through animal membranes, as in the distribution of poisons, gases, etc., through the body. Unlike absorption, diffusion may go on after death, that is, after the blood ceases to circulate.

Syn: Extension; spread; propagation; circulation; expansion; dispersion.

Source: Webster's Revised Unabridged Dictionary (1913)