diffuser

American  

[dih-fyoo-zer] / dɪˈfju zər /

Or diffusor

noun

• diffusers
  plural

1. a person or thing that diffuses.

2. (in various machines or mechanical systems, as centrifugal pumps or compressors) a device for utilizing part of the kinetic energy of a fluid passing through a machine by gradually increasing the cross-sectional area of the channel or chamber through which it flows so as to decrease its speed and increase its pressure.

3. (in a lighting fixture) any of a variety of translucent materials for filtering glare from the light source.

4. a pierced plate or similar device for distributing compressed air for aeration of sewage.

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diffuser British  

/ dɪˈfjuːzə /

noun

1. a person or thing that diffuses

2. a part of a lighting fixture consisting of a translucent or frosted covering or of a rough reflector: used to scatter the light and prevent glare

3. a cone, wedge, or baffle placed in front of the diaphragm of a loudspeaker to diffuse the sound waves

4. a duct, esp in a wind tunnel or jet engine, that widens gradually in the direction of flow to reduce the speed and increase the pressure of the air or fluid

5. photog a light-scattering medium, such as a screen of fine fabric, placed in the path of a source of light to reduce the sharpness of shadows and thus soften the lighting

6. a perforated plate or similar device for distributing compressed air in the aeration of sewage

7. a device, attached to a hairdryer, which diffuses the warm air as it comes out

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Other Word Forms

Noun Inflected Forms

• diffusers
  plural

Etymology

Origin of diffuser

First recorded in 1670–80; diffuse + -er ¹

Example Sentences

See Examples For:

diffuser diffusers

They will also carry a portable scent diffuser throughout the experience.

From Barron's ● Jun. 19, 2026

Consider the overbalance of gloss-black surfaces—not just the grille form but the roof, roof racks, roof pillars, bumpers, mirror caps, rear diffuser thingy, deep-tinted rear glass and heavy window masking.

From The Wall Street Journal ● May 30, 2026

The fundamental aerodynamic philosophy is a return to so-called 'step-plane' cars, with a flat bottom either side of the central chassis reference plane, with a diffuser at the back.

From BBC ● Dec. 9, 2025

A diffuser can help spread fragrance throughout your home for an extended period of time.

From Seattle Times ● Feb. 20, 2024

The styling and drying process was extremely complicated—Mari wrapped individual strands of hair around the handle of a comb and then used a hairdryer with a diffuser attachment on each individual curl.

From "Keeping Pace" by Laurie Morrison

His response: "Everything is out of stock - candles, diffusers."

From BBC ● Jan. 9, 2026

It recently installed scent diffusers with its Fresh Balsam fragrance in New York City’s Grand Central Terminal to accompany its messaging for four weeks.

From The Wall Street Journal ● Nov. 25, 2025

“From forecasting demand and budgeting to producing our candles, diffusers and seasonal gift collections months in advance.”

From MarketWatch ● Nov. 8, 2025

But the efficacy of diffusers can vary, depending on the species of mosquito.

From Los Angeles Times ● Jul. 29, 2024

Scents of lavender spit out from oil diffusers placed strategically throughout the venue.

From "Kwame Crashes the Underworld" by Craig Kofi Farmer