"Decimate"
What’s the Trouble? Some people cling to the belief that decimate can only mean “reduction by 10%.”
Here’s some background: The Roman military wasn’t as interested in justice as it was in order. We get the word “decimate” from the Romans’ brutal practice of punishing mutinous units by having the men draw lots, and then requiring the troops who were to survive to kill the unlucky 10 percent who chose the wrong lot.
“Decimate” has its etymological root in the Latin word for “tenth,” and it shares that root with words like “decimal” and “decimeter.” Because of these historical and etymological roots, some people believe that the only proper way to use “decimate” is to talk about something reduced by precisely 10 percent.
Usage experts disagree. The Merriam-Webster Dictionary of English Usage (MWDEU), for example, notes that “decimate” has never been used this way in English. Although there is an entry for the “reduction by 10 percent” meaning in the Oxford English Dictionary (OED), it contains no example sentences, which is unusual. The MWDEU editors believe that the OED definition was included merely to bridge the gap between the Roman practice and the standard English meaning, which is “a massive or severe reduction.”
What Should You Do? Use “decimate” without fear to describe a huge culling or loss. Because of its roots, “decimate” is particularly well used when describing significant casualties in a population of military troops or another group of people, but it can be used to describe any extreme loss.
Beware of using it to describe death or a complete loss, however. Those uses are incorrect.
Who, in the midst of passion, is vigilant against illness? Who listens to the reports of recently decimated populations in Spain, India, Bora Bora, when new lips, tongues and poems fill the world?
— Lauren Groff in the book Delicate Edible Birds: And Other Stories