1867, Latinized from osmose (1854), shortened from endosmosis (1830s), from endosmose "inward passage of a fluid through a porous septum" (1829), from French endo- "inward" + Greek osmos "a thrusting, a pushing," from stem of othein "to push, to thrust," from PIE *wedhe- "to push, strike" (cf. Sanskrit vadhati "pushes, strikes, destroys," Avestan vadaya- "to repulse"). Figurative sense is from 1900. Related: Osmotic (1854, from earlier endosmotic).
osmosis os·mo·sis (ŏz-mō'sĭs, ŏs-)
n. pl. os·mo·ses (-sēz)
Diffusion of fluid through a semipermeable membrane until there is an equal concentration of fluid on both sides of the membrane.
The tendency of fluids to diffuse in such a manner.
The movement of a solvent through a membrane separating two solutions of different concentrations. The solvent from the side of weaker concentration usually moves to the side of the stronger concentration, diluting it, until the concentrations of the solutions are equal on both sides of the membrane. ◇ The pressure exerted by the molecules of the solvent on the membrane they pass through is called osmotic pressure. Osmotic pressure is the energy driving osmosis and is important for living organisms because it allows water and nutrients dissolved in water to pass through cell membranes.
Note: Informally, “osmosis” is the process by which information or concepts come to a person without conscious effort: “Living in Paris, he learned French slang by osmosis.”