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[oz-moh-sis, os-] /ɒzˈmoʊ sɪs, ɒs-/
Physical Chemistry, Cell Biology.
  1. the tendency of a fluid, usually water, to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of materials on either side of the membrane.
  2. the diffusion of fluids through membranes or porous partitions.
a subtle or gradual absorption or mingling:
He never studies but seems to learn by osmosis.
Origin of osmosis
1865-70; Latinized form of now obsolete osmose osmosis, extracted from endosmose endosmosis, exosmose exosmosis < French, equivalent to end- end-, ex- ex-2 + Greek ōsm(ós) push, thrust + French -ose -osis
Related forms
[oz-mot-ik, os-] /ɒzˈmɒt ɪk, ɒs-/ (Show IPA),
osmotically, adverb
nonosmotic, adjective
nonosmotically, adverb
unosmotic, adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2018.
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Examples from the Web for osmosis
Historical Examples
  • In other words, it receives its nourishment from the mother by absorption or osmosis.


    William J. Robinson
  • I do believe in the osmosis of evil, in the diffusion of villainy, in the corruption of the soul.

    After the Rain Sam Vaknin
  • Without the process of osmosis we should be unable to use much of the food we eat.

    A Civic Biology George William Hunter
  • It then passes into the cells by osmosis, and there becomes part of the cell sap.

    A Civic Biology George William Hunter
  • Nourishment passes through them by a simple process of osmosis.

    Embryology Gerald R. Leighton
  • The first experiment in physiogeny was the discovery of osmosis by the Abb Nollet in 1748.

    The Mechanism of Life Stphane Leduc
  • This osmosis is an indispensable condition in the vital process.

    Are the Planets Inhabited? E. Walter Maunder
  • The peptones and sugar pass by osmosis into the blood-vessels of the portal system and thence to the liver.

  • The molecular concentration of tissue and blood fluid is constantly being equalized by the process of osmosis.

    Disease and Its Causes

    William Thomas Councilman
  • The interchange between the fluid outside the vessels and the blood fluid takes place by means of filtration and osmosis.

    Disease and Its Causes

    William Thomas Councilman
British Dictionary definitions for osmosis


/ɒzˈməʊsɪs; ɒs-/
the passage of a solvent through a semipermeable membrane from a less concentrated to a more concentrated solution until both solutions are of the same concentration
diffusion through any membrane or porous barrier, as in dialysis
gradual or unconscious assimilation or adoption, as of ideas
Derived Forms
osmotic (ɒzˈmɒtɪk; ɒs-) adjective
osmotically, adverb
Word Origin
C19: Latinized form from osmose (n), from Greek ōsmos push, thrust
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for osmosis

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).

Online Etymology Dictionary, © 2010 Douglas Harper
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osmosis in Medicine

osmosis os·mo·sis (ŏz-mō'sĭs, ŏs-)
n. pl. os·mo·ses (-sēz)

  1. Diffusion of fluid through a semipermeable membrane until there is an equal concentration of fluid on both sides of the membrane.

  2. The tendency of fluids to diffuse in such a manner.

os·mot'ic (-mŏt'ĭk) adj.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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osmosis in Science

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.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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osmosis in Culture
osmosis [(ahz-moh-sis, ahs-moh-sis)]

The seeping of a fluid through a seemingly solid barrier, such as a cell wall or a rubber sheet. When the concentration of the fluid is the same on both sides of the barrier, osmosis stops.

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.”
The New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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