Today, a brief thought about word usage – specifically, the words defuse and diffuse.
People who make it their business to provide guidance and/or scolding on such matters like to use this as a classic example of homophone (or near-homophone, depending on your accent) abuse. There are dozens of instances of people writing about diffusing a bomb, or a situation, and then being sniggered at by grammarians.
And it’s true, of course, that you can’t diffuse a bomb or a situation. You can only de-fuse it, i.e. remove its fuse, i.e. its explosive capacity.
But what you most certainly can do is diffuse tension. That is, if the tension is likened to an intense atmospheric presence – like, say, the outcome of a notably fierce fart – then you can lessen its effect by dispersing it or spreading it about, as with the air released when you burst a balloon, or the mitigation of a fart by wafting.
You can’t defuse tension. That makes no sense, because that suggests that afterwards the tension is somehow still there, only without its fuse. I can’t even visualise that. You need to suggest the dispersal – i.e. the destruction – of the tension. Which is why diffuse is correct in this context.
I suspect that this use of diffuse might count as an eggcorn.
There’s more on this subject by the deeply wise and admirably non-judgmental sages at Language Log here.