The verbs “diffuse” and “defuse” are often confused with each other.
Diffuse means to spread out or scatter freely or randomly. Think of pouring cream in your coffee or tea and not stirring it. The “clouds in your coffee” will undergo the process of diffusion as natural molecular motions put the second law of thermodynamics into effect to maximize entropy or disorder.
After the rodeo’s opening performance was over, the record crowd diffused throughout Houston.
Defuse means to make less harmful or tense, or to calm. Think of removing a fuse from a stick of dynamite. This is what my hubby did in the Air Force as part of his explosive ordnance disposal duties. His job was to locate unexploded bombs and “render them safe,” which is military parlance for “blow them up.” Apparently he was successful at doing so, because he still has all his fingers – but his hearing is not so great. Those bombs were definitely safer, less harmful, “defused” when he was finished.
Leaders in Tunisia, Egypt, and Libya gave in to some of the protesters’ demands in the hopes of defusing the angry crowds.
Hopefully I have infused you with enough knowledge that you won’t be confused about diffused and defused any longer.