What is a non-example of diffusion?

A non-example of diffusion is a brick.

Diffusion is termed as movement of molecules from a region of high concentration to a region of low concentration. A good example is how oxygen enters the body during external respiration which is referred to as breathing.

Some of examples of diffusion are diffusion of mineral salt in the soil water into the root hairs cells. Diffusion of oxygen into the carbon dioxide and cell out of the cell in a unicellular like an amoeba, Diffusion of oxygen through the lungs and carbon dioxide out to the lungs of mammals.

Diffusion of carbon dioxide and oxygen out by the leaf through the stomata.