That’s part of page 105 of the 1952 edition of Fowler’s Dictionary of Modern English Usage. I looked up the word after I read the plot summary in the Wikipedia entry about the film Inferno (2016), which currently says:
[The villain’s bioweapon has] the potential of decimating the world’s population.
It could be argued that a 50% reduction in the world’s population, technically, does not count as “decimating”, since—as has been smugly pointed out—the meaning of “decimate” is etymologically tied to a figure of 10%.
In fact, it’s been argued (even more smugly) that “decimate” had another, earlier meaning, which was financial in nature; supposedly “decimate” meant “tithe”.
I think I agree with Fowler that “decimate” can now legitimately mean “destroy a large proportion” but should still be avoided when the context contains a specific proportion.
See below for more on my reasons for (finally) ceasing to believe exclusively in the historical meaning and my thoughts on how to carefully use the word in its widely accepted modern sense.
What’s the basis of the die-hard defense of the 10% meaning?
Well, historically, as you know if you’ve read Colleen McCullough’s excellent and rather bulky Masters of Rome book series, “decimation” was a punishment suffered by a defeated legion of Roman soldiers. The commanders of a legion that had been shamefully defeated would order the soldiers to kill one of every ten of their own men. They used some civilized, orderly process like drawing straws. The unlucky man got clubbed to death by the other nine. Since these ten guys had known each other, fought together, and survived a losing battle together, I don’t imagine the nine survivors felt much relief at being the murderers rather than the victim.
The resulting army, smaller by exactly 10%, was thought to be thereby adequately punished for its failure and adequately prepared to succeed in the next battle. The impact of decimation was mathematically small, but psychologically huge.
The word “decimation” contains the Latin root for “tenth”, which you can easily recognize in the word “decimal”. The prefix “deci” is also found throughout the metric system of measurements in words such as “decimeter” and “deciliter”, though these are less common than “centimeter” and “milliliter”.
Pointing to the etymology of the word, purists could argue that to “decimate” something is to destroy a tenth of it, no more. Something which is mostly or completely wiped out cannot thus be said to be “decimated”.
I admit that this bit of pedantry has some appeal to it; all other things being equal, shouldn’t we preserve the information embedded in the word, handed down to us by history? Is it not embarrassingly ignorant and ungrateful not to do so? Well, yes. All other things being equal.
What’s the descriptivist (majority) view?
According to descriptivism, a word means whatever people want it to, if they’re even the tiniest bit consistent. That bothers me ideologically, but I don’t think the current use of “decimate” is anything to get upset about.
In fact, I’ve come to think that “decimate” is perhaps not a bad way to denote the action of causing a near-total or even a total loss. To the extent that the word is being carelessly used as a supposedly exact but “fancier” synonym for “destroy”, “devastate”, “obliterate”, or “annihilate”, that’s truly a shame, but at least some of the time it’s not being used that way, and it’s hard to see how the word ever could be used in its “original” military sense, since (thankfully) we no longer punish soldiers by making them murder each other.
I think people say “decimated” when there has been a substantial loss that carries with it a large negative emotional impact. The percentage loss of life is not the key aspect of the word’s meaning now, or perhaps even historically. After all, it wasn’t the number of soldiers who died but how they were put to death that most affected the survivors. We use “decimate” when we want to denote a loss which is shockingly bad. How else could we convey exactly that?
“Devastate” describes the emotional impact only; it’s usually not an action verb but a participle (devastated, devastating) used as an adjective.
“Destroy” describes the action of causing something to cease to be. Destruction can be good: you could say that Superman destroyed an asteroid that had been on a collision course with earth, but you couldn’t rightly say he decimated it. (Did he detonate it? Er—maybe? Was he carrying explosives, or did he just punch it or something?)
“Obliterate” describes the action of causing something to cease to be in a way that is so total that people forget it existed. It has a connotation of erasure, and can be used in connection with abstract things like memories, which—at least in the normal course of things—are never physically destroyed.
“Annihilate” also conveys a sense of completeness about the destruction in question. It means to make something into “nihil”—nothing. I also feel like the word must be used in situations involving a kind of righteous rage; one does not annihilate dispassionately. An unthinking robot or heartless alien could destroy or obliterate us, but could it be said to have annihilated us in that case? I think not.
Conclusion
The way in which the underperforming Roman soldiers were decimated was that a tenth of them were murdered by their fellows, but there are many ways in which decimation can occur which have as little to do with that particular numeric proportion as they have to do with Roman soldiers.
The Rubicon is crossed, the die is cast. “Decimate” is yours to use as you see fit.
Just don’t, you know, overdo it, or you’re guilty of what Fowler calls SLIPSHOD EXTENSION*.
Words often mean something different than what they used to mean, but that doesn’t mean they mean whatever you want them to.
*Fowler’s explanation of “slipshod extension” from page 541 of the 1952 edition of Fowler’s Dictionary of Modern English Usage:
Slipshod extension is especially likely to occur when some accident gives currency among the uneducated to words of learned origin, & the more if they are isolated or have few relatives in the vernacular…. [The unlearned language user—male, by convention, because this is 1952—arrives at such a word’s meaning] by observing what is the word known to him with which it seems to be exchangeable… and his next step is to show off his new acquisition… as often as he can, without at all suspecting that the two are very imperfect synonyms…. He perhaps notices now & then that people look at him quizzically as if he were not quite intelligible, but this happens seldom enough to let him put it comfortably down to their ignorance of the best modern idiom…. He is injuring the language, however unconsciously, both by helping to break down a serviceable distinction, & by giving currency to a mere token word in the place of one that is alive.
