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.
And there’d be no diffusion and none of that in Buffalo, for example. Mark Hughes, Forbes.com, 30 May 2025 Like other modern video generation models, Veo 3 is built on diffusion technology—the same approach that powers image generators like Stable Diffusion and Flux. ArsTechnica, 29 May 2025 This bi-dimensional diffusion panel provides audio multi-reflection on both vertical and horizontal planes, and works especially well on mid and high frequencies, helping to enhance musical definition. Chris Haslam, Wired News, 23 May 2025 The Commerce Department on Monday officially rescinded the former Biden administration’s artificial intelligence diffusion rule that would have placed caps on chip sales to most countries around the world. Miranda Nazzaro, The Hill, 13 May 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

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Cite this Entry

“Diffusion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diffusion. Accessed 29 Jun. 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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