Defuse vs. diffuse

To defuse (something) is to make a threatening or dangerous situation safer. For example, you might defuse a violent argument by calming the people involved, or you might literally defuse a bomb by deactivating its fuse. Diffuse works as both a verb and an adjective. To diffuse something is to disperse it or spread it out. When something is dispersed or spread out, it is diffuse.

Because diffuse works as an adjective, diffused is only necessary as a verb form. Defuse doesn’t work as an adjective, so defused is the proper form in phrases such as the defused bomb.


These writers use defuse well:

If someone started a fight, he was the one who would defuse the situation. [The World Link]

Alice Springs police were called to an Indigenous camp yesterday to defuse threats of a violent riot. [ICNN]

The adjectival sense of diffuse is much more common than the verb. These writers use it well:

The benefits of globalisation have been diffuse while its downsides have largely been isolated. [The National]

It is about 1.5 times as wide as Jupiter, but only about a tenth as dense, making it one of the most diffuse planets yet found. [New Scientist]

But the verb appears occasionally:

We’ll look at ideas to diffuse the sound or bounce it away. [Brooklyn Paper]

There is nothing here to diffuse the focus: it’s on Porsches, everywhere, all the time. [NY Times]

Confusion of defuse and diffuse is so common that we actually had some difficulty finding examples of diffuse used correctly. Here are just a few of the problematic examples we found:

It’s difficult to diffuse this much dynamite. [Times Leader]

Police negotiated with Finnegan in an attempt to diffuse the situation. [Cape Cod Online]

Attempts to diffuse the bomb failed. [The Epoch Times]

6 thoughts on “Defuse vs. diffuse”

  1. What is the relationship between the ‘fuse’ components of confuse, diffuse, and defuse? I always believed the ‘fuse’ in defuse refers to the wick of an explosive charge, whereas the ‘fuse’ of diffuse and confuse must refer to some form of subcomponents (such as particles). But now I’m well.. confused.

    • It has a lot to do with root words. For defuse, it’s pretty recent, and it literally means to un-fuse or remove the fuse.

      Confuse comes from confundere, which is Latin for “mingle together.” It’s very closely related to confound, which I hope helps–it doesn’t come from the same root as defuse, so it shouldn’t be seen as “fuse with” (even though, in a way, that’s exactly what the root word means).

      Diffuse comes from disfundere, or “pour away.” It’s more closely related to confuse than defuse.

  2. Maybe it’s my engineering background, but diffuse the verb seems WAY more common than diffuse the adjective to me. “The gas particles diffused through the chamber.”

    • Heh, it’s just the opposite in computer graphics. Diffuse light, diffuse vs specular reflection. “Diffuse map” even became a de-facto stand in for albedo. But if we are talking about the behavior of photons or volumetrics we usually use “scatter” instead of the verb diffuse.


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