The near-homophones defuse and diffuse can give writers and editors some trouble. Spellcheck certainly can’t save you from them, and understanding the words’ meanings is only half the solution. These words are easy for our eyes to slide over while we’re reading, making the error easy to miss and correct. They’re like time bombs waiting there in the text.
Not ticking time bombs. Bombs with, you know, fuses.
Defuse literally means “to remove the fuse from” — the bomb, mine, cannon or firecracker kind of fuse, not the old-fashioned turned-too-many-appliances-on-at-once-and-now-the-fuse-has-blown kind. Because few of us regularly deal with timed explosions, defuse is often used to describe deactivating something that could metaphorically explode, like a tense situation or an angry uncle’s ire.
Kendall defused the tense standoff between the SWAT team and the Portland Hipster Corps by cracking open a can of soda and offering it to the most eligible bachelor on the police force.
To diffuse something is to cause it to spread freely, and often thinly or wastefully. Bryan Garner helpfully points out that though we usually consider that the thing being diffused is diminished as it spreads — a drop of dye becomes less concentrated as it diffuses in water, for example — that isn’t always the case. Some things, like ideas or technologies, grow in both size and strength as they diffuse.
Jaime switched on the radiator and then burrowed back under her thick duvet until the heat diffused throughout the room.
Diffuse can also mean “simultaneously verbose and badly organized.”
I reckon readers of Copyediting.com have few problems differentiating the meanings of diffuse and defuse. For copyeditors, the difficulty comes in identifying when the wrong one has been used as we’re reading through texts. Spellcheck will be of no help to you here.
Over time, every copyeditor develops a mental list — maybe even a physical one — of “stop words.” These are the words that writers often confuse or misspell or that get misused or overused. The list likely also includes embarrassing errors that the editor missed at some point. When we find a stop word in a manuscript, we (surprise!) stop and focus on that specific word to make sure it’s correct.
My stop words include very and literally (which are ripe for deletion), canceled and traveled (to count the ls), and sacrilegious (to check the spelling), as well as the word pairs you’ll find in just about any listicle of commonly confused words: affect/effect, altar/alter, and so on.
Defuse and diffuse are also on that list of mine, and they should be on your list, too. Any time you see either of these words, pause and make sure the right one is used. It only takes a heartbeat, and that heartbeat can save you from an embarrassing error.