View your list of saved words. (You can log in using Facebook.)
Spontaneous passage or diffusion of water or other solvent through a semipermeable membrane. If a solution is separated from a pure solvent by a membrane that is permeable to the solvent but not to the solute, the solution will tend to become more dilute by absorbing solvent through the membrane. The pressure caused by the migration of solvent through the membrane is called osmotic pressure.
This entry comes from Encyclopædia Britannica Concise. For the full entry on osmosis, visit Britannica.com.