Usage of diffuse vs. defuse

I often hear phrases such as "infantry were sent in to diffuse/defuse the situation," and I am never quite sure which people are saying, and which is correct. Both seem to make sense.

To me (a chemist/physicist) the primary definition of the intransitive verb "diffuse" has a very specific meaning: to move randomly through a medium. I also understand the transitive verb "diffuse" to mean to make something less concentrated, or to lower its energy.

"Defuse," on the other hand, has one clear meaning: to remove the fuse from a bomb (or situation), making it less dangerous.

So the question is, when I hear "diffuse/defuse the situation," is there a more correct word to use, or is this a case where words are both homophones and synonyms? (Which would be pretty cool.)

Solution 1:

Defuse the situation is the more sensible of the two:

It employs the metaphor that the situation is a bomb, and may explode. Defusing it will render it harmless.

Diffusing a situation would mean to spread it out and make it less concentrated. You can make a case that the intensity of the situation needs diffusion to make it less dangerous, but I believe it to be a stretching of the metaphor to the point where it seems to really be a mangling of defuse.

Note, both are commonly used, so it's not really wrong to use diffuse.

Solution 2:

'Defuse is a verb, which means 'to remove the fuse'. But it is often used figuratively, such as in 'UN forces were sent in to help defuse the tensions between the warring parties'.

'Diffuse, is also a verb, meaning to 'spread over a wide area, or among a larger number of people' such as 'the problem is how to diffuse power without creating anarchy'. But 'diffuse' is more frequently used as an adjective meaning 'widespread', or 'not concentrated'. 'Lacking clarity, the second proposal is more diffuse'.