diffusion

noun

dif·​fu·​sion di-ˈfyü-zhən 

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 

adjective

Synonyms

• circumlocution
• diffuseness
• garrulity
• garrulousness
• logorrhea
• long-windedness
• periphrasis
• prolixity
• redundancy
• verbalism
• verbiage
• verboseness
• verbosity
• windiness
• wordage
• wordiness

Examples of diffusion in a Sentence

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

Recent Examples on the Web

President Wants ‘Fair Deals’ With Other Countries—But Unlikely Before Midnight Deadline Google’s Android Update—Bad News For Samsung And Pixel Users How does diffusion work? —John Werner, Forbes.com, 8 Apr. 2025

In February, John Smedley launched a diffusion line, JS by John Smedley, which is sold exclusively at John Lewis, that retails for $56 to $239, below the average of $305 in its core line. —Hikmat Mohammed, Footwear News, 7 Apr. 2025

Complicating matters, the Trump administration hasn’t articulated its position on implementing the Biden administration’s artificial intelligence diffusion regulations, scheduled to take effect May 15, which will particularly impact Nvidia’s export controls. —Kristina Partsinevelos, CNBC, 3 Apr. 2025

Three criteria – depth, diffusion, and duration – need to be met individually to some degree to formally identify a recession, according to the NBER. —Rachel Barber, USA Today, 7 Apr. 2025

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

Rhymes for diffusion

• allusion
• collusion
• conclusion
• confusion
• contusion
• delusion
• effusion
• exclusion
• extrusion
• illusion
• inclusion
• infusion

Kids Definition

diffusion

noun

dif·​fu·​sion dif-ˈyü-zhən 

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 

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 

adjective