diffusion

noun

dif·​fu·​sion di-ˈfyü-zhən How to pronounce diffusion (audio)
Synonyms of diffusionnext
1
: the state of being spread out or transmitted especially by contact : the action of diffusing
the diffusion of knowledge
2
: prolixity, diffuseness
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
di-ˈfyü-zhə-nᵊl How to pronounce diffusion (audio)
adjective

Synonyms of diffusion

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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.
The real opportunity may lie in slow diffusion and integration, a less marketable but potentially sound thesis. — Josipa Majic Predin, Forbes.com, 7 Aug. 2026 Researchers assumed that corals were passive with respect to the slow-moving boundary layer, simply relying on natural diffusion through it to provide nutrients and oxygen. — Marlowe Starling, Quanta Magazine, 5 Aug. 2026 Even though these are technically a semi-sheer, the curtain panels can give you a bit more privacy and more of a light-filtering sheer than a true light diffusion. — Kate McGregor, Architectural Digest, 4 Aug. 2026 Open models strengthen safety and cybersecurity, accelerate innovation and diffusion, and enable sovereignty. — Aamir Khollam, Interesting Engineering, 24 July 2026 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

Rhymes for diffusion

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Browse Nearby Words

diffusibility
diffusion
diffusion coefficient
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Cite this Entry

“Diffusion.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/diffusion. Accessed 10 Aug. 2026.

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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
-ˈyüzh-nəl, -ən-ᵊl How to pronounce diffusion (audio)
adjective

More from Merriam-Webster on diffusion

Nglish: Translation of diffusion for Spanish Speakers

Britannica.com: Encyclopedia article about diffusion

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