DECIMATE

            This word means “to reduce by one-tenth,” and does not mean annihilate or devastate, as it is often used.

            Its origin goes back to the Roman Empire, where it was used as a punishment for cowardly or unsuccessful soldiers.

            Imagine, if you will, a Roman general standing before an offending line of soldiers, ordering them to count off, over and over, one to ten, then directing that every number three be killed. Undoubtedly the survivors would make every effort to avoid such an offense in the future.

            There have been cases throughout history where this method of discipline was applied to civilians, sometimes to the residents of entire villages.

            When such action is taken against human beings, it is grotesquely violent, but if, for example, a mouthwash were to advertise that it “decimates the bacteria that can cause disease,” it wouldn’t be very effective.

            If you want to say an event wiped out most of a group, “devastate” is more accurate than “decimate.”