Diffusion

Noun

1. The act of diffusing or dispersing something, or the property of being diffused or dispersed; dispersion.
2. The scattering of light by reflection from a rough surface, or by passage through a translucent medium.
3. The intermingling of the molecules of a fluid due to random thermal agitation.

   "gaseous diffusion"

4. The spread of cultural or linguistic practices, or social institutions, in one or more communities.
5. The gradual spread and adoption of goods or services.