View your list of saved words. (You can log in using Facebook.)
Process by which there is a net flow of matter from a region of high concentration to one of low concentration. It occurs fastest in liquids and slowest in solids. Diffusion can be observed by adding a few drops of food colouring to a glass of water. The scent from an open bottle of perfume quickly permeates a room because of random motion of the vapour molecules. A spoonful of salt placed in a bowl of water will eventually spread throughout the water.
This entry comes from Encyclopædia Britannica Concise. For the full entry on diffusion, visit Britannica.com.