President Trump recently used the word “decimate” several times to describe U.S. military strikes on Iran. In an April 1 address about Operation Epic Fury he said, “We’ve beaten and completely decimated Iran. They are decimated both militarily and economically.” Today many people hear “decimate” and understand it to mean “destroy” or “devastate,” but the word’s history is more specific.
Etymologist Michiel de Vaan traces decimate to the Latin decimatio, from decimus, meaning “tenth.” In ancient Rome decimatio named a particular form of military punishment: when a unit was judged culpable of cowardice or mutiny, the troops drew lots and every tenth man was executed—often by the other nine in the group. The practice was rare but brutally effective, intended to shock survivors into discipline while not wiping out an entire unit. Classical historians such as Plutarch and Appian record a famous instance in 72 B.C., when Marcus Licinius Crassus ordered a decimation after a unit fled during the war against Spartacus. Scholars like Barry Strauss have suggested Crassus may have seen a dramatic penalty as necessary to restore order amid a serious insurrection and to bolster his political standing.
So how did a term meaning “kill one-tenth” become a synonym for wholesale destruction? Part of the shift comes from parallel uses in contexts such as tithing, where taking a tenth was an established concept. After the fall of Rome the term largely fell out of common use, only to be revived by Renaissance and later classical scholars. Over time its sense broadened: first to the idea of leaving only one-tenth, and by the mid-17th century it had acquired a more general sense of severe loss or devastation.
That drift has annoyed some language purists. In 1870 Richard Grant White criticized Civil War writers for using “decimate” to mean total slaughter, and Lake Superior State University placed the word on its 2008 list of banished words. Still, many editors and linguists point out that language changes with usage. As NPR copy editor Preeti Aroon put it when defending a contested usage, “Meanings change over time.” Understanding the word’s origins—both its precise Roman meaning and its later evolution—can clarify how and why people use “decimate” today.