osmosis

[ oz-moh-sis, os- ]

noun

1. 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. Compare endosmosis, exosmosis.
2. a subtle or gradual absorption or mingling:

   He never studies but seems to learn by osmosis.

osmosis

/ ɒzˈməʊsɪs; ɒzˈmɒtɪk; ɒs-; ɒs- /

noun

1. 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
2. diffusion through any membrane or porous barrier, as in dialysis
3. gradual or unconscious assimilation or adoption, as of ideas

osmosis

/ ŏz-mō′sĭs /

1. 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.
2. ◆ 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.

osmosis

1. 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.

Notes

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.”

Derived Forms

• osˈmotically, adverb
• osmotic, adjective

Other Words From

• os·mot·ic [oz-, mot, -ik, os-], adjective
• os·moti·cal·ly adverb
• nonos·motic adjective
• nonos·moti·cal·ly adverb
• unos·motic adjective

Word History and Origins

Origin of osmosis¹

First recorded in 1865–70; Latinized form of obsolete osmose, extracted from endosmose endosmosis ( def ), exosmose exosmosis ( def ), from French, equivalent to end- end-, ex- ex- ² + Greek ōsm(ós) “a push, thrust” + French -ose -osis

Word History and Origins

Origin of osmosis¹

C19: Latinized form from osmose (n), from Greek ōsmos push, thrust

Example Sentences

Pitcher filters are simple, but their long-term cost can be higher than that of adsorption or reverse osmosis filters installed under the sink.

From Salon

I’ve inherited some things through osmosis but, by and large, I didn’t know the first thing about Judaism — even having been bar mitzvahed, having played Jewish characters before.

From Los Angeles Times

Typically, he added, they can be treated using activated carbon and reverse osmosis.

From Los Angeles Times

Living organisms use osmosis for such activities as bursting seed dispersing fruits in plants or absorbing water in the intestine.

From Science Daily

If artistic stature worked by osmosis, Christian Wolff could claim greatness based on that alone.

From New York Times

More About Osmosis

What is osmosis?

Osmosis is the movement of a fluid from an area with a low concentration of a solute through a semipermeable membrane to an area with a high concentration of a solute.

A solute is something that dissolves in something else, known as a solvent, creating a solution. In sugar water (a solution), the sugar is the solute that dissolves in the water, the solvent. Concentration is the measurement of how much solute is in a solvent. Semipermeable means that only certain things can pass through something. In osmosis, only the solvent (usually water) can pass through the membrane.

The process of osmosis works like this. Let’s say we have a glass that is separated down the middle with a plastic divider with tiny holes in it that only water can move through. First, we fill the glass with water. Then, we add 5 grams of salt to one half of the glass and 7 grams of salt to the other half. What happens?

Over time, water will flow from the half with 5 grams of salt (the lower concentration) into the half with 7 grams of salt (the higher concentration). Water will stop flowing (or flow incredibly slowly) when the two halves have about the same amount of salt in each side.

Osmosis is a natural process that a solvent will want to do. Both plants and animals use osmosis to absorb water into their highly concentrated cells. Without osmosis these living things would be more likely to suffer from dehydration.

Why is osmosis important?

The first records of the term osmosis come from around 1865. It is the Latinized form of the obsolete noun osmose, which comes from the Greek word osmos, meaning “push” or “thrust.” In osmosis, a solvent “pushes” or “thrusts” through a membrane.

Water is the most common solvent involved in osmosis because of how prevalent and important it is. Importantly, osmosis is a passive process, which means cells don’t have to spend energy to perform it. Water will naturally flow into the cells.

Osmosis is a sort of fluid version of a process known as diffusion, in which something of high concentration moves to an area of low concentration. In the case of osmosis, a solvent with less stuff in it is highly concentrated so it wants to move through a barrier to help fill an area with more solute that is taking up space and making the solvent around it less concentrated.

Did you know … ?

Osmosis is used outside of science to refer to any passive flow or absorption. For example, we might describe a student as learning “through osmosis,” meaning they don’t actively study but gradually absorb the knowledge over time.

What are real-life examples of osmosis?

Osmosis is a process that is commonly learned by students new to biology or chemistry.

It's best to learn about osmosis by hanging around people who know the subject and just sort of let it sink in.

— Milton Mermikides (@miltonline) April 24, 2012

If I sleep with my textbook under my pillow, will I absorb the info through osmosis?

— jordan (@BallanceJordan) September 21, 2020

 

What other words are related to osmosis?

• diffusion
• solute
• solvent
• concentration
• equilibrium
• semipermeable
• membrane

Quiz yourself!

True or False?

During osmosis, water flows from an area with a high concentration of solute through a membrane into an area with a low concentration of solute.