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."

Definitions of diffuse
  1. adjective
    spread out; not concentrated in one place
    “a large diffuse organization”
    spread out or scattered about or divided up
  2. adjective
    lacking conciseness
    “a diffuse historical novel”
    tediously prolonged or tending to speak or write at great length
  3. adjective
    (of light) transmitted from a broad light source or reflected
    synonyms: diffused, soft
    see moresee less
    concentrated, hard
    (of light) transmitted directly from a pointed light source
  4. verb
    move outward
    synonyms: fan out, spread, spread out
    see moresee less
    show 5 types...
    hide 5 types...
    spread gradually
    grow or spread, often in such a way as to cover (a surface)
    bleed, run
    be diffused
    spread over a surface, like a mantle
    release color when rubbed, of badly dyed fabric
    type of:
    distribute, spread
    distribute or disperse widely
  5. verb
    spread or diffuse through
    synonyms: imbue, interpenetrate, penetrate, permeate, pervade, riddle
    see moresee less
    spiritise, spiritize
    imbue with a spirit
    type of:
    penetrate, perforate
    pass into or through, often by overcoming resistance
  6. verb
    cause to become widely known
    synonyms: broadcast, circularise, circularize, circulate, disperse, disseminate, distribute, pass around, propagate, spread
    circulate, go around, spread
    become widely known and passed on
    see moresee less
    show 4 types...
    hide 4 types...
    distribute (multimedia files) over the internet for playback on a mobile device or a personal computer
    introduce into an environment
    generalise, generalize, popularise, popularize, vulgarise, vulgarize
    cater to popular taste to make popular and present to the general public; bring into general or common use
    carry, run
    include as the content; broadcast or publicize
    type of:
    air, bare, publicise, publicize
    make public
Word Family

Test prep from the experts

Boost your test score with programs developed by’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week


  • Number of words: 700+
  • Duration: 10 weeks
  • Time: 1 hour / week