diffuse

American  

[dih-fyooz, dih-fyoos] / dɪˈfjuz, dɪˈfjus /

verb (used with object)

• diffuses,
  present (3rd person singular)
• diffused,
  past participle,  past
• diffusing
  present participle

1. to pour out and spread, as a fluid.

2. to spread or scatter widely or thinly; disseminate.

3. Physics. to spread by diffusion.

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verb (used without object)

• diffuses,
  present (3rd person singular)
• diffused,
  past participle,  past
• diffusing
  present participle

1. to spread.

2. Physics. to intermingle by diffusion.

adjective

1. characterized by great length or discursiveness in speech or writing; wordy.

2. widely spread or scattered; dispersed.

3. Botany. widely or loosely spreading.

4. Optics. (of reflected light) scattered, as from a rough surface (opposed to specular).

diffuse British  

/ dɪˈfjuːzəbəl, dɪˈfjuːslɪ /

verb

1. to spread or cause to spread in all directions

2. to undergo or cause to undergo diffusion

3. to scatter or cause to scatter; disseminate; disperse

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adjective

1. spread out over a wide area

2. lacking conciseness

3. (esp of some creeping stems) spreading loosely over a large area

4. characterized by or exhibiting diffusion

   diffuse light

   diffuse reflection

5. botany (of plant growth) occurring throughout a tissue

Commonly Confused

See defuse

Other Word Forms

Derived Forms

• diffuseness
  noun
• diffusibility
  noun
• overdiffuseness
  noun
• interdiffuse
  verb
• overdiffuse
  verb
• rediffuse
  verb
• diffusible
  adjective
• nondiffuse
  adjective
• nondiffused
  adjective
• nondiffusing
  adjective
• undiffused
  adjective
• well-diffused
  adjective
• diffusely
  adverb
• overdiffusely
  adverb

Inflected Forms

Participles

• diffusing
  present
• diffused
  past

Conjugated Forms

Present

• diffuse
  simple
• diffuses
  simple
• have diffused
  perfect
• has diffused
  perfect
• am diffusing
  progressive
• are diffusing
  progressive
• is diffusing
  progressive
• have been diffusing
  perfect progressive
• has been diffusing
  perfect progressive

Past

• diffused
  simple
• had diffused
  perfect
• was diffusing
  progressive
• were diffusing
  progressive
• had been diffusing
  perfect progressive

Future

• will diffuse
  simple
• will have diffused
  perfect
• will be diffusing
  progressive
• will have been diffusing
  perfect progressive

Etymology

Origin of diffuse

1350–1400; Middle English (< Anglo-French ) < Latin diffūsus spread, poured forth. See dif-, fuse ²

Explanation

Diffuse means to spread out. Candlelight can diffuse a soft glow throughout a room. A diffuse idea is one that spreads from person to person, and a diffuse speech is scattered and unclear. As a verb, diffuse means to spread something out, but also applies to spreading things such as ideas or culture so that they become widely known. When something is diffused, it's mixed in, and when you drop propaganda pamphlets out of airplanes you're diffusing the propaganda. The adjective comes from Latin diffusus, from diffundere "to pour in different directions," from the prefix dis- "apart" plus fundere, "to pour."

Example Sentences

See Examples For:

diffuse diffuses diffused diffusing

Third, Chandra detected only very weak diffuse X-ray emission.

From Science Daily ● Aug. 2, 2026

An attempt to detonate or diffuse the bomb failed, so Officer Brian Murray and three others were lowered into the crater.

From Slate ● Jul. 7, 2026

Its benefits—cognitive diversity, locally fitted rules, parallel experimentation, choice among competing jurisdictions, and interpretations truer to what Congress enacted—are diffuse and hard to measure.

From The Wall Street Journal ● Jun. 24, 2026

"A formal hierarchy still remains in Tehran, but in practice, power and authority are likely exercised in a more fragmented and diffuse manner," said Sabet.

From Barron's ● Jun. 4, 2026

Instead, the utility of the wheel surely caused it to diffuse rapidly east and west over the Old World from its sole site of invention.

From "Guns, Germs, and Steel: The Fates of Human Societies" by Jared M. Diamond

The glass is screened by adjustable curtains of a high-tech fabric that diffuses and softens the sunlight, making it ideal for viewing the three-dimensional art displayed there.

From The Wall Street Journal ● Apr. 17, 2026

The physical act of twirling noodles while discussing something as monumental as coming out diffuses the tension just enough for honesty to survive.

From Salon ● Feb. 15, 2026

Dunst diffuses the moment by adopting an exaggerated Valley girl sing-song, “I basically fell in love with Cailee and I was like, ‘She’s the best, you need to work with her.’”

From Los Angeles Times ● Apr. 4, 2024

It borrows an idea from physics that can be used to describe, for instance, how gas diffuses outward.

From Seattle Times ● Mar. 4, 2024

The square of sunshine moves, diffuses, grows faint yellow.

From "The Boy Who Dared" by Susan Campbell Bartoletti

On “Quotidien,” the audience is seated in a circle around the stars, which calls for the studio lights to be spread out around them, creating a softer, more diffused effect.

From The Wall Street Journal ● Mar. 22, 2026

Xu and team argue that any systems breakthrough or efficiency gains are diffused quickly across the ecosystem.

From MarketWatch ● Feb. 16, 2026

“Oprah’s Favorite Things was a phenomenon because of how trusted Oprah was, so it really is that same phenomenon, just diffused across the creator ecosystem.”

From Los Angeles Times ● Oct. 18, 2025

Draper quickly diffused what could have been a tricky encounter, showing his superior quality and experience from the start.

From BBC ● May 31, 2025

By the living room door was a narrow space that ended in the frosted-glass door of the front entrance through which a diffused blood-orange light embossed the beige and olive wallpaper in fiery honeycomb patterns.

From "Atonement" by Ian McEwan

Add to this growing critical mineral-processing capacity, vast AI training data generated by India’s large population, and the potential role of Indian IT companies in diffusing AI to less technologically advanced economies.

From The Wall Street Journal ● Jul. 1, 2026

Participants will be working on shared language for annexes covering child protection, AI security and governance and diffusing AI through economies -- especially to small and medium firms.

From Barron's ● May 29, 2026

Every time you say, “Let them,” even if it’s after the outburst, you’re still diffusing the emotion.

From Los Angeles Times ● Mar. 5, 2025

"These companies begin by diffusing trust in the medical and pharmaceutical industry, advertising themselves as a safer option, highlighting how GLP-1 medications are more dangerous and encouraging using ‘natural’ alternatives."

From Salon ● Jan. 10, 2025

Eleanor wasn't diffusing, but she was using the conditioner Park's mom had given her.

From "Eleanor & Park" by Rainbow Rowell