diffuse

American  

[dih-fyooz, dih-fyoos] / dɪˈfyuz, dɪˈfyus /

verb (used with object)

diffused, diffusing

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

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

3. Physics. to spread by diffusion.

---

verb (used without object)

diffused, diffusing

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

---

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

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

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

That effort might also diffuse some tension caused by the addition of transitional kindergarten, which took away many 4-year-olds from an already struggling child-care industry, Fuller said.

From Los Angeles Times • Apr. 21, 2026

It defers it to a moment when Iran’s alternative financial infrastructure is more mature, more diffuse, and more difficult to address than it is today.

From Barron's • Apr. 18, 2026

This structure shows that magnetized plasma is being dragged through the cluster, leaving behind a diffuse trail that has persisted for millions of years.

From Science Daily • Apr. 13, 2026

“Just talking through it with the people that are actually helping to diffuse AI through the economy across every single industry” is “exactly what we’re going to continue to do,” Hays added.

From MarketWatch • Apr. 3, 2026

However, the particular spectral lines observed are often characteristic of very thin, diffuse gas, and not the astonishingly high density that must prevail near black holes.

From "Cosmos" by Carl Sagan