diffuser

or dif·fu·sor

[ dih-fyoo-zer ]

Phonetic (Standard)IPA

noun

a person or thing that diffuses.
(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.
(in a lighting fixture) any of a variety of translucent materials for filtering glare from the light source.
a pierced plate or similar device for distributing compressed air for aeration of sewage.

diffuser

/ dɪˈfjuːzə /

a person or thing that diffuses
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
a cone, wedge, or baffle placed in front of the diaphragm of a loudspeaker to diffuse the sound waves
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
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
a perforated plate or similar device for distributing compressed air in the aeration of sewage
a device, attached to a hairdryer, which diffuses the warm air as it comes out

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

It seems probable that he was a diffuser of knowledge rather than an originator, but as a great teacher his fame is secure.

Here is an example of Spenser's diffuser style, taken from the second book of the Faerie Queene.

The old idea of a librarian was that of a guardian or keeper of books—not a diffuser of knowledge, but a mere custodian of it.

The most conspicuous addition made by Mr. Boyden was the diffuser.

Fix the charcoal well with a spray diffuser and the usual solution of white shellac in spirits of wine.

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