[ verb dih-fyooz; adjective dih-fyoos ]
See synonyms for: diffusediffuseddiffusesdiffusing on Thesaurus.com

verb (used with object),dif·fused, dif·fusing.
  1. to pour out and spread, as a fluid.

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

  1. Physics. to spread by diffusion.

verb (used without object),dif·fused, dif·fusing.
  1. to spread.

  2. Physics. to intermingle by diffusion.

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

  2. widely spread or scattered; dispersed.

  1. Botany. widely or loosely spreading.

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

Origin of diffuse

1350–1400; Middle English (<Anglo-French ) <Latin diffūsus spread, poured forth. See dif-, fuse2

Other words from diffuse

  • dif·fuse·ly [dih-fyoos-lee], /dɪˈfyus li/, adverb
  • dif·fuse·ness, noun
  • in·ter·dif·fuse, verb, in·ter·dif·fused, in·ter·dif·fus·ing.
  • non·dif·fuse, adjective
  • non·dif·fused, adjective
  • non·dif·fus·ing, adjective
  • o·ver·dif·fuse, verb, o·ver·dif·fused, o·ver·dif·fus·ing, adjective
  • o·ver·dif·fuse·ly, adverb
  • o·ver·dif·fuse·ness, noun
  • re·dif·fuse, verb, re·dif·fused, re·dif·fus·ing.
  • un·dif·fused, adjective
  • well-dif·fused, adjective

Words that may be confused with diffuse

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use diffuse in a sentence

  • Is memory made apt and extensive or narrow and diffusely irrelevant?

  • In Section 106 we learned that most objects are visible to us because of the light diffusely reflected from them.

    General Science | Bertha M. Clark
  • He seemed a trifle sulky, but he did not talk about himself diffusely, and lose his head when he was smoothed the right way.

    T. Tembarom | Frances Hodgson Burnett
  • "Let me have the pleasure of telling it you my way," cried she, and told it diffusely, and kept him writhing.

    White Lies | Charles Reade
  • Are the sensitive cells diffusely distributed in the organ or do they form a definite layer?

British Dictionary definitions for diffuse


  1. to spread or cause to spread in all directions

  2. to undergo or cause to undergo diffusion

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

  1. spread out over a wide area

  2. lacking conciseness

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

  2. characterized by or exhibiting diffusion: diffuse light; diffuse reflection

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

Origin of diffuse

C15: from Latin diffūsus spread abroad, from diffundere to pour forth, from dis- away + fundere to pour

confusable For diffuse

Avoid confusion with defuse

Derived forms of diffuse

  • diffusely (dɪˈfjuːslɪ), adverb
  • diffuseness, noun
  • diffusible (dɪˈfjuːzəbəl), adjective
  • diffusibility or diffusibleness, noun

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012