from
The Collaborative International Dictionary of English v.0.48
osmosis \os*mo"sis\ ([o^]z*m[=o]"s[i^]s), n. [NL., fr. Gr.
'wsmo`s, equiv. to 'w^sis impulse, fr. 'wqei^n to push.]
(Chemical Physics)
(a) The tendency in fluids to mix, or become equably
diffused, when in contact. It was first observed between
fluids of differing densities, and as taking place
through a membrane or an intervening porous structure. An
older term for the phenomenon was {Osmose}.
Note: The more rapid flow from the thinner to the thicker
fluid was then called {endosmosis} (formerly
{endosmose}), and the opposite, slower current,
{exosmosis} (formerly {exosmose}). Both are, however,
results of the same force. Osmosis may be regarded as a
form of molecular attraction, allied to that of
adhesion. See also {osmotic pressure}.
(b) The action produced by this tendency.
[1913 Webster]