diffusion

noun

dif·​fu·​sion di-ˈfyü-zhən How to pronounce diffusion (audio)
1
: the state of being spread out or transmitted especially by contact : the action of diffusing
the diffusion of knowledge
2
3
a
chemistry : the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal (see thermal entry 1 sense 1b) agitation and in dissolved substances move from a region of higher to one of lower concentration
b physics
(1)
: reflection of light by a rough reflecting surface
(2)
: transmission of light through a translucent material : scattering
4
: the spread of cultural elements from one area or group of people to others by contact
5
photography : the softening of sharp outlines in an image
diffusional adjective

Examples of diffusion in a Sentence

the author's tendency toward diffusion makes the novel a tedious read
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
This is a classic example of diffusion of responsibility, where leaders can wriggle out of being held accountable by pointing the finger elsewhere. Melissa A. Wheeler, Forbes.com, 30 June 2025 His unorthodox policy views had a magnifying effect on major global trends that had been well underway before Trump was elected, including the global diffusion of power, rapid and disruptive technological change, and political polarization and policy volatility. Rebecca Lissner, Foreign Affairs, 24 June 2025 The same trends of cord-cutting and social media diffusion are affecting Canadian broadcasters and streamers. Cynthia Littleton, Variety, 19 June 2025 Sur believes that management has good visibility for solid growth through calendar year 2026, backed by recent mega data center deals (including those with UAE, Saudi Arabia, and Taiwan) and the end of the diffusion rule. Tipranks.com Staff, CNBC, 8 June 2025 See All Example Sentences for diffusion

Word History

Etymology

Middle English diffusioun "outpouring (of speech)," borrowed from Late Latin diffūsiōn-, diffūsiō "pouring out (of liquids), watering of the eyes, abundance" (Latin, "geniality"), from Latin diffud-, variant stem of diffundere "to pour out over a wide surface, spread out, extend" + -tiōn-, -tiō, suffix of verbal action — more at diffuse entry 2

First Known Use

15th century, in the meaning defined at sense 2

Time Traveler
The first known use of diffusion was in the 15th century

Browse Nearby Words

Cite this Entry

“Diffusion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diffusion. Accessed 9 Jul. 2025.

Kids Definition

diffusion

noun
dif·​fu·​sion dif-ˈyü-zhən How to pronounce diffusion (audio)
1
: a diffusing or a being diffused
2
: the mixing of particles of liquids, gases, or solids so that they move from a region of high concentration to one of lower concentration
3
: the scattering of light by reflection from a rough surface or by passage through a translucent material (as frosted glass)

Medical Definition

diffusion

noun
dif·​fu·​sion dif-ˈyü-zhən How to pronounce diffusion (audio)
1
: the process whereby particles of liquids, gases, or solids intermingle as the result of their spontaneous movement caused by thermal agitation and in dissolved substances move from a region of higher to one of lower concentration
2
a
: reflection of light by a rough reflecting surface
b
: transmission of light through a translucent material
diffusional adjective

More from Merriam-Webster on diffusion

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