Misnegation is an obscure word for a common phenomenon. You won’t find it in dictionaries, but you can probably figure out that it means some kind of ‘incorrect negation’ – not to be confused with double negatives (‘multiple negation’), criticism of which tends to be dubious.
So what exactly are we talking about here?
Misnegation is where we say something with negatives in it that don’t add up the way we intend. We lose track of the logic and reverse it inadvertently. For example, I might say that the likelihood of misnegation cannot be understated, when I mean it cannot be overstated – it is, in fact, easily understated.
Misnegation often occurs with overstate or understate, overestimate or underestimate, but it can take many, many forms. It pops up in all sorts of places, including large print on official signs, as this example from Helen Stevens shows. Even Hägar the Horrible once said, ‘I miss not having’ when he really meant ‘I miss having’: