diffusion

noun dif·fu·sion \ di-ˈfyü-zhən \

|Updated on: 22 Jun 2018

Definition of diffusion

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 ¹thermal 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

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diffusional

play \-ˈfyü-zhə-nᵊl\ adjective

See diffusion defined for kids

Examples of diffusion in a Sentence

the author's tendency toward diffusion makes the novel a tedious read

Recent Examples of diffusion from the Web

The researchers thoroughly tested the children’s reading skills and assessed their brain architecture using diffusion magnetic resonance imaging.

— susan pinker, WSJ, "New Skills Build New Brain Architecture, Research Shows," 14 June 2018
Bureaucracies are excellent blame-diffusion machines.

— justin davidson, Daily Intelligencer, "A Year Has Passed Since the Grenfell Tower Fire. It Could Happen Again Anytime.," 14 June 2018
The centrifuges themselves don’t take up much floor space, so their plants have a much smaller physical footprint than gaseous diffusion facilities.

— umair irfan, Vox, "Uranium enrichment will be a key point in talks with North Korea. Here’s what it is.," 11 June 2018
Outside of Earth’s gravity, protein molecules move and therefore crystalize via randomized diffusion.

— joe pappalardo, Popular Mechanics, "How Space Crystals Could Lead To New Cancer Drugs," 5 June 2018
An examination of the electrode showed that, over time, diffusion of the catalyst drew it into larger and larger bubbles, and the diameter of the nanotubes grew accordingly.

— john timmer, Ars Technica, "Process takes CO₂ from the air, converts it to carbon nanotubes," 30 May 2018
His dream’s desert daylight diffusion dictated disturbances in the void of visual detail.

— john warner, chicagotribune.com, "Sean Penn's new novel doesn't deserve a considerate review — or a reader's time," 3 Apr. 2018
Liebhold contends that advancement in technology and a concomitant diffusion of industry also played a key role in the upsurge of free trade.

— ryan p. smith, Smithsonian, "A History of America’s Ever-Shifting Stance on Tariffs," 13 Apr. 2018
Elsewhere, panels of bronze mesh evoke the diffusion filter on a condenser microphone, dispersing the visual resonance.

— christopher knight, latimes.com, "Rashid Johnson at David Kordansky Gallery: Power, protection, plus 'Ugly Pots'," 5 May 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'diffusion.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

Origin and Etymology of diffusion

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 ²diffuse

NEW! Time Traveler

First Known Use: 15th century

in the meaning defined at sense 2

See Words from the same year

Other Physics Terms

amplitude, centrifugal, centripetal, convection, gradient, hysteresis, kinetic, lase, quantum

DIFFUSION Defined for Kids

diffusion

noun dif·fu·sion \ di-ˈfyü-zhən \

Definition of diffusion for Students

1 : the act of spreading or allowing to spread freely

2 : the mixing of particles of liquids or gases so that they move from a region of high concentration to one of lower concentration

Medical Dictionary

diffusion

noun dif·fu·sion \ dif-ˈyü-zhən \

medical Definition of diffusion

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

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