If you've been following the news lately, you might have noticed that a certain word has suddenly become a favorite of President Trump's: "decimate."
He has used it a lot to describe U.S. military action against Iran. Take, for example, part of his April 1 address to the nation about Operation Epic Fury: "We've beaten and completely decimated Iran. They are decimated both militarily and economically."
Today, most people know the word as a synonym for "destroy." But fewer realize its origins — or that it's come to mean something strikingly different than it once did.
Michiel de Vaan, an etymologist at the University of Basel in Switzerland, says decimate traces back to the Latin decimatio, by way of decimus, meaning a tenth. In its original Latin form, decimatio "meant to take out and kill one-tenth of a group of soldiers," he says.
It meant something very specific — a brutal form of discipline, not a vague notion of widespread destruction, de Vaan notes.
A "decimation" was a punishment meted out by the legionaries of the Roman army on their own comrades "in cases where an entire group of soldiers had typically been guilty of something like cowardice on the battlefield," according to Gregory Aldrete, a professor emeritus of history at the University of Wisconsin-Green Bay.
What was a Roman decimation?
Such punishment was rarely inflicted, but when it did occur, it was carried out with cold-blooded efficiency, Aldrete says. "They would have the group that they wanted to punish randomly draw lots, and every tenth soldier was then clubbed to death by nine others."
The idea behind this punishment was that sacrificing 10% of an army's soldiers was sufficient to create a lasting impression on the others, deterring future misbehavior without losing too much military strength.
The Roman historians Plutarch and Appian both mention an example of decimation in 72 B.C., during the Third Servile War. General Marcus Licinius Crassus was fighting the famed Roman gladiator Spartacus, who was leading a major slave uprising against Rome. In an engagement against the rebels, one unit ran from the battlefield. In turn, Crassus ordered a decimation.
Ever since, "historians have wondered why he did it," says Barry Strauss, a senior fellow at the Hoover Institution at Stanford University.
The speculation is that Spartacus' insurrection had been a serious threat to Roman rule; his group of rebels ravaged southern Italy and defeated multiple Roman legions. Crassus "might have thought that the army really needed to be shocked out of its behavior," Strauss says, adding: "The Romans could be very violent, but the Romans [were] also extremely pragmatic."
Strauss notes that Crassus was "a very ambitious politician" who "wouldn't have done it unless he thought that he could get away with it."
How did decimate become synonymous with destroy?
De Vaan says around the time the word was being used to describe a military punishment, another form of it also popped up in some translations of the Bible — where "to take a tenth" referred to a person tithing 10% of their income to the church.
Sometime between the end of the Roman Empire and the Renaissance, the word seems to have largely disappeared before being resurrected by classical scholars, he says. And not long after, de Vaan says, the definition flip-flopped: "The meaning becomes to leave only one tenth" and more commonly still, a synonym for destruction.
By about the middle of the 17th century, it was being used simply to mean "devastate."
Since that time, the word has become nearly every pedant's pet peeve. American essayist Richard Grant White, in his 1870 book Words and Their Uses, Past and Present: A Study of the English Language, described a Civil War correspondent's use of the word to mean as a synonym for wholesale slaughter as "simply ridiculous."
In 2008, Lake Superior State University placed "decimate" on its annual list of banished words, suggesting that "word-watchers have been calling for its annihilation" for years because of its perceived misuse.
For some, however, the semantic struggle lives on. NPR copy editor Preeti Aroon recalls that when she worked for Foreign Policy magazine, an executive editor approached her. "He said that a reader had emailed us about allegedly using the word 'decimate' incorrectly in an article." She pushed back. "Meanings change over time," she told him.
"Language does evolve over time," Aroon adds. Any older generation, she says, is likely to be annoyed at the way younger generations use the language. But "the reality is the older generation dies out. So the younger generation's word choices … [are] pretty much always going to win out."
Copyright 2026 NPR