Talk to any committed language peever,* and sooner or later you’ll hear about decimate: that it properly means ‘kill one in ten’ and should not be used to mean ‘destroy a large proportion of’ or ‘inflict great harm or damage on’. This is because decimate originally referred to a practice in the Roman army of executing one in ten men in mutinous groups.
It’s the etymological fallacy: the belief that a word’s older or original meaning is the only correct one or is automatically more correct than newer, conventionally accepted ones. Words that repeatedly elicit the fallacy include aggravate, alternative, dilemma, fulsome, refute, and transpire. It’s often a vehicle for pedantic or snobbish triumphalism: I acquired this knowledge, and you didn’t, so I must display it.
Decimate is infamous in editorial circles for this reason. My rule, featured in the A–Z of English usage myths, is that if you say decimate can only mean ‘kill one in ten’, you must also call October ‘December’. (See also: quarantine for any period other than 40 days, etc.) For authoritative discussion, browse the usage notes in a few good dictionaries, starting with AHD.
The broader sense of decimate dates to at least 1660. Since then, according to the Merriam-Webster Dictionary of English Usage, it is
the only sense of the word that has continued to thrive in English. It is an emphatic word, and probably owes its continued use in English to the arbitrary ferocity of the Roman practice rather than to its arithmetic.
The original meaning is now vanishingly rare. I looked at 400 random examples of decimate(s/d) in contemporary English – 200 in the NOW Corpus, for professional prose; 200 in the GloWbE Corpus, for less formal styles – and found none with the sense ‘kill one in ten’. To assert this as the sole legitimate meaning is to double down on delusion, and to obliterate (decimate, even) any claims one might make to linguistic authority.
But decimate in the sense ‘kill one in ten’ is not entirely obsolete. I came across a nice example in Jonathan Franklin’s book 438 Days:
Although sharks are demonized as man-eaters the equation is actually the other way around. For the roughly ten annual fatal shark attacks on earth, the world’s fishermen slaughter approximately twenty million sharks a year, many of which end up as shark steaks on a dinner plate. Severe overfishing has produced the literal decimation of shark populations (only 10 percent remaining) in the last half century, making contemporary shark science akin to extrapolation from the survivors of a global genocide.
I have nothing against the original meaning and was pleased to see it in the wild, though struck too by the need to modify it with literal and clarify it with a parenthetical gloss. Drift gonna drift.
438 Days was described by Outsider magazine as ‘the best survival book in a decade’. Among other things, it’s a gripping case study of human isolation. An apt read for these strange times.
* Some call them grammar nazis, a term I avoid for reasons that I hope are obvious.