diffuse

verb

dif·​fuse di-ˈfyüz 

diffused; diffusing

transitive verb

1

a

: to pour out and permit or cause to spread freely

a drop of blue dye diffused in a glass of water

b

: extend, scatter

diffusing their ideas throughout the continent

c

: to spread thinly or wastefully

a government in which power is diffused

2

physics : to subject to diffusion (see diffusion sense 3)

especially : to break up and distribute (incident light) by reflection

put up a screen to diffuse the light

intransitive verb

1

: to spread out or become transmitted especially by contact

The civilization diffused westward.

2

: to undergo diffusion

heat from the radiator diffusing throughout the room

diffusible

di-ˈfyü-zə-bəl 

adjective

Frequently Asked Questions

What is the difference between diffuse and defuse?

Many people find it difficult to remember the difference between defuse and diffuse, and when faced with the need for one of these words simply grab whichever one first comes to mind. Although these words sound quite similar, their meanings are rather distinct. Defuse means "to make less harmful, potent, or tense"; the word has another, helpfully literal, meaning, which is "to remove the fuse from." Diffuse means "not concentrated or localized"; it comes from the Latin word diffūsus ("spread over a wide area").

What is the difference between diffuse and infuse?

Diffuse is commonly found used as both adjective ("not concentrated or localized") and verb ("to pour out and permit or cause to spread freely," "to scatter"), while infuse is almost entirely restricted to use as a verb. While the meannings of diffuse are mainly concerned with outward movement, those of infuse are inward; the word has such meanings as "to steep in liquid (such as water) without boiling so as to extract the soluble constituents or principles," "to administer or inject by infusion," and "to cause to be permeated with something (such as a principle or quality) that alters usually for the better."

What does diffuse pain mean?

Diffuse pain is pain that is not concentrated or localized, being instead spread throughout a wider area of the body.

Examples of diffuse in a Sentence

The heat from the radiator diffuses throughout the room.

The heat was diffused throughout the room.

The photographer uses a screen to diffuse the light.

an area of diffused light

Recent Examples on the Web

The matte, micro-textured surface diffuses incoming light, whether under bright stage lighting or natural daylight, the screen maintains a steady presentation while automatically adjusting its brightness. —William Jones, USA Today, 3 June 2026

Responsibility diffuses across humans, models, and data. —Tomas Chamorro-Premuzic, Forbes.com, 27 May 2026

Layer monochromatic textures Lighter colors diffuse sunlight and reflected throughout a small bedroom. —Yelena Moroz Alpert, Architectural Digest, 25 May 2026

Tottenham went from being a club where all power was concentrated in one person to one where it was diffused between many. —Jack Pitt-Brooke, New York Times, 25 May 2026

Word History

Etymology

Middle English, in past participle diffusid, borrowed from Latin diffūsus, past participle of diffundere "to pour out over a wide surface, spread out, extend, squander," from dif-, assimilated form of dis- dis- + fundere "to pour, shed" — more at found entry 5

First Known Use

15th century, in the meaning defined at transitive sense 1a

Phrases Containing diffuse

• diffuse-porous

Rhymes for diffuse

• abstruse
• abuse
• adduce
• atreus
• caboose
• cayuse
• conduce
• deduce
• disuse
• excuse
• footloose
• induce

Kids Definition

diffuse

1 of 2 adjective

dif·​fuse dif-ˈyüs 

1

: using too many words : verbose

a diffuse writer

2

: poured or spread out : not concentrated

diffuse daylight

diffusely adverb

diffuseness noun

diffuse

2 of 2 verb

dif·​fuse dif-ˈyüz 

diffused; diffusing

1

: to pour out and permit or cause to spread freely

2

: to go through or cause to go through diffusion

Medical Definition

diffuse

1 of 2 adjective

dif·​fuse dif-ˈyüs 

: not concentrated or localized

diffuse sclerosis

diffuse

2 of 2 verb

dif·​fuse dif-ˈyüz 

diffused; diffusing

transitive verb

1

: to subject (as a light beam) to diffusion

2

: to break up and distribute (incident light) by reflection (as from a rough surface)

intransitive verb

: to undergo diffusion