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.)