os·​mo·​sis | \ äz-ˈmō-səs How to pronounce osmosis (audio) , äs- \

Definition of osmosis

1 : movement of a solvent (such as water) through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane
2 : a process of absorption or diffusion (see diffusion sense 3a) suggestive of the flow of osmotic action especially : a usually effortless often unconscious assimilation (see assimilation sense 4) learned a number of languages by osmosis— Roger Kimball

Examples of osmosis in a Sentence

She seems to learn foreign languages by osmosis.
Recent Examples on the Web Aldridge isn’t going to pick up Duncan’s omnipresent competitive fire via osmosis, as much as San Antonio would love him to do so. Mike Finger, ExpressNews.com, "Aldridge remains a mystery the Spurs don’t try to explain," 10 Nov. 2019 Many early social-media entrepreneurs went to college to study computer science or business, receiving a respect for free-speech principles via cultural osmosis. Andrew Marantz, The New Yorker, "The Dark Side of Techno-Utopianism," 23 Sep. 2019 Pushing water across a membrane requires adding pressure to force water to move against its natural tendency of osmosis. Ula Chrobak, Popular Science, "To solve global water scarcity, we need to get more serious about desalination," 30 Dec. 2019 The process of moving water across a semipermeable membrane is called osmosis. Svenja Lohner, Scientific American, "Make a Potato Shrink--with Saltwater," 9 Jan. 2020 Eventually, much of life is learned through the osmosis of what feels right — patterns that become ingrained in our brains and hard to change. Monica Hesse, Washington Post, "A grammar nerd gently dismantles your arguments for rejecting the new ‘they’," 20 Sep. 2019 The water then goes through reverse-osmosis to screen out organic material, salts and other solids. David Garrick, San Diego Union-Tribune, "San Diego’s landmark water recycling program halted by dispute over union workers," 27 Sep. 2019 One station accommodates large containers, which customers can fill up for 35 cents a gallon for reverse-osmosis-filtered water. San Diego Union-Tribune, "Part supermarket, part food hall: New Carmel Valley Jimbo’s opens its doors," 18 Sep. 2019 That’s kind of sunk in, even in a non-conscious way, sort of by osmosis. Taylor Weatherby, Billboard, "Adam Lambert May Tour With Queen, But Prince Was His True Inspiration For 'Velvet: Side A'," 27 Sep. 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'osmosis.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of osmosis

1863, in the meaning defined at sense 1

History and Etymology for osmosis

earlier osmose in same sense + -osis, after endosmosis, exosmosis; osmose generalized from endosmose "passage through a membrane from a region of lower to a region of higher concentration" and exosmose "passage through a membrane from a region of higher to a region of lower concentration" (later endosmosis, exosmosis), both borrowed from French, from end- end-, ex- ex- entry 2 + -osmose, from Greek ōsmós "push, thrust" (from ōthéō, ōtheîn "to push, thrust" + -(s)mos, resultative noun suffix) + French -ose -osis; ōthéō, ōtheîn probably going back to Indo-European *h2u̯odhh1-, iterative derivative of *h2u̯edhh1- "thrust," whence also Sanskrit ávadhīt "(s/he) has struck, has slain"

Note: The terms endosmose and exosmose were introduced by the French physician and physiologist Henri Dutrochet (1776-1847) in L'agent immédiat du mouvement vital dévoilé dans sa nature et dans son mode d'action, chez les végétaux et chez les animaux (Paris, 1826), p. 126: "Ainsi, lorsque c'est le plus dense des deux fluides qui est dans la cavité, l'eau y est introduite par l'action que j'ai nommée endosmose; lorsqu'au contraire c'est le plus dense des deux fluides qui est hors de la cavité, le fluide le moins dense, qui est au dedans, est poussé au dehors par une action inverse que je nommerai exosmose.[footnote] (1) Mot dérivé de ἐξ, dehors, et de ωσμος, impulsion." ("Thus when the denser of the two fluids is inside the cavity, the water is drawn in by the action that I term endosmose; when on the contrary the denser of the two fluids is outside the cavity, the less dense fluid, which is inside, is pushed outward by an inverse action that I term exosmose. (1) Word derived from ex, outside, and from ōsmos, impetus.") The reconstruction *h2u̯odhh1- is from R. Beekes, Etymological Dictionary of Greek (Brill, 2010), with Greek -ōth- presumed to be a contraction from *awoth-. Beekes rejects the suggestion by Chantraine (Dictionnaire étymologique de la langue grecque) that ōtheîn is the durative form of a verb *éthein allegedly seen in éthōn, a present participle of obscure meaning that occurs twice in the Iliad (and hence parallel, according to Chantraine, with the lengthened grade seen in pōléomai "go/come frequently" as against pélomai "become, take place").

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The first known use of osmosis was in 1863

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Cite this Entry

“Osmosis.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/osmosis. Accessed 8 Aug. 2020.

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More Definitions for osmosis


How to pronounce osmosis (audio)

English Language Learners Definition of osmosis

biology : the process that causes a liquid (especially water) to pass through the wall of a living cell
: an ability to learn and understand things gradually without much effort


os·​mo·​sis | \ äs-ˈmō-səs How to pronounce osmosis (audio) , äz- \

Kids Definition of osmosis

: a passing of material and especially water through a membrane (as of a living cell) that will not allow all kinds of molecules to pass


os·​mo·​sis | \ äz-ˈmō-səs How to pronounce osmosis (audio) , äs- How to pronounce osmosis (audio) \
plural osmoses\ -​ˌsēz How to pronounce osmoses (audio) \

Medical Definition of osmosis

: movement of a solvent through a semipermeable membrane (as of a living cell) into a solution of higher solute concentration that tends to equalize the concentrations of solute on the two sides of the membrane

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Rhyming Dictionary: Words that rhyme with osmosis

Spanish Central: Translation of osmosis

Nglish: Translation of osmosis for Spanish Speakers

Britannica.com: Encyclopedia article about osmosis

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