What does osmosis mean?
Osmosis is the spontaneous movement of a solvent, most often water, across a selectively permeable membrane. Water moves from a region of lower solute concentration toward one of higher solute concentration, continuing until equilibrium is reached or another force opposes the flow. This physical process gives its name to related vocabulary, especially the adjective osmotic. In ordinary usage, osmosis can also describe the gradual absorption or diffusion of ideas, habits, tastes, and influence: something becomes widely accepted not through a single dramatic act but through repeated exposure. That figurative use often suggests change that is subtle, passive, and difficult to notice. Osmosis is therefore useful in both science and criticism, naming a precise natural mechanism while also capturing how communities absorb cultural trends. In biology, the term usually refers specifically to solvent movement, not the movement of dissolved particles, which is called diffusion.
nounThe spontaneous movement of a solvent across a selectively permeable membrane from a region of lower solute concentration to one of higher concentration. By extension, it refers to the gradual assimilation of ideas, influences, or characteristics through constant exposure.
- The spontaneous movement of a solvent across a selectively permeable membrane from a region of lower solute concentration to one of higher concentration.
- The gradual absorption or transmission of ideas, habits, influences, or characteristics through constant exposure.
"Reverse osmosis purifies seawater by drawing dissolved salts through a selectively permeable membrane."
"Reverse osmosis purifies seawater by drawing dissolved salts through a selectively permeable membrane."
"Through the slow osmosis of daily exposure, the phrase became part of the public vocabulary."
The plural is rare in general use and is chiefly appropriate when counting distinct instances of the process.
"The experiment recorded two osmoses under different concentrations."
Osmosis lets water climb through a membrane without anyone squeezing it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of osmosis
The word entered English through New Latin from Greek osmōsis, meaning “a pushing,” which was derived from osmos, “push,” related to the Greek verb oistēmi, “I push.” Its early scientific use developed from this sense of pressure or movement through a membrane. English derivatives such as osmotic, osmometer, osmology, and osmography all continue this Greek root.
Related word forms
How osmosis is actually used
In scientific contexts, osmosis is normally an uncountable noun and refers specifically to solvent movement. Its figurative use is common in discussions of culture, language, fashion, and public opinion, where it often emphasizes gradual and less obvious influence.
Easily confused with osmosis
Diffusion is the general net movement of particles down a concentration gradient, whereas osmosis specifically concerns solvent moving across a selectively permeable membrane.