osmosis

noun

os·​mo·​sis äz-ˈmō-səs 

äs-

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

Engineering electricity from salinity gradients PRO systems work through osmosis, the process by which water molecules move from an area of low salt concentration to a high concentration across a semipermeable membrane. —Tejasri Gururaj, Interesting Engineering, 24 Oct. 2025

For so many others the osmosis is slower and less conspicuous—the constant stress on one’s nerves from underpay and overwork and the rent being too high and our world, generally, being wholly unfair. —P.e. Moskowitz september 11, Literary Hub, 11 Sep. 2025

Walther will sleep in a forward compartment, and drink water supplied by a Schenker reverse-osmosis water maker. —New Atlas, 8 Sep. 2025

Still, Love Island managed to maintain momentum and stay relevant due to an ability it, along with other successful reality shows, excel at: what can only be described as cultural osmosis. —Braedon Montgomery, Forbes.com, 29 Aug. 2025

Word History

Etymology

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").

First Known Use

1863, in the meaning defined at sense 1

Phrases Containing osmosis

• reverse osmosis

Rhymes for osmosis

• cirrhosis
• fibrosis
• gliosis
• hypnosis
• ichthyosis
• ketosis
• kurtosis
• lordosis
• meiosis
• miosis
• mitosis
• mycosis

Kids Definition

osmosis

noun

os·​mo·​sis äz-ˈmō-səs 

äs-

1

: the passage of material (as a solvent) through a membrane (as of a plant or animal cell) that will not allow all kinds of molecules to pass

2

: a taking in (as of knowledge) as if by the process of osmosis

osmotic

-ˈmät-ik

adjective

Medical Definition

osmosis

noun

os·​mo·​sis äz-ˈmō-səs  äs- 

plural osmoses -ˌsēz 

: 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