We should stop calling the Islamic State “medieval.” We use that word for rhetorical effect but fail to appreciate how much doubt it conveys. It’s a mistake to reach for special vocabulary to intensify our condemnation of “this medieval and vile movement,” as Nick Clegg, deputy prime minister of the U.K., recently described it. What happened to British understatement? Take Clegg’s remark, delete “medieval and,” keep “vile,” and rearrange the letters: The Islamic State is evil. That’s enough. Resist the temptation to pile on more words. They weaken the assertion. More is less.

Another reason that the specific adjective “medieval” in this context rings false is that it is — it’s factually wrong. “We still talk of ‘the Middle Ages’ because it is a convenient term for the millennium stretching from the fall of Rome to the Reformation — frankly nobody can think of a better one,” this historian at Leicester University recently explained. “But was it brutal? Taken in the round, the period was no more violent than what came before or afterwards.” This British sociologist goes further, arguing that present-day jihadism, far from being medieval, is “a modern, anti-traditional ideology, with a very significant debt to [modern] western political history and culture.”

Granted, Islamists themselves are wont to invoke Islam’s founding and early period, which occurred during the Middle Ages, and so we have justification for using the “m” word — but then we don’t, because its force is not limited to simply denoting a certain span of centuries. It goes on to connote a negative moral judgment of the age, as when Secretary of State John Kerry called the beheading of Steven Sotloff “medieval savagery.” The estimable Victor Davis Hanson, a historian, used the same stock phrase in reference to the Islamic State back in June.

It’s understandable. Deadlines loom. We don’t always have time to sit back and sift through our lexical storehouse, trying out this item and then that until we hit on the mot juste. “Medieval” sounds pretty damning, and we mean to condemn, so maybe that’s good enough. Not long ago I edited an article in which the author spelled it “midevil.”

Still, why the double standard? We don’t speak of the Thirty Years’ War as “Renaissance savagery” or of Robespierre, who knew a few things about beheading, as “an Enlightenment-era cutthroat.” We single out the Middle Ages and make them the byword for human bloodlust. It’s a categorical slur against all our ancestors who are too young to share in the halo of classical antiquity but too old to be considered one of us, good citizens of modernity.

“So what?” you might think. “They’re dead to us. If the memory of them becomes collateral damage in our verbal aggression against a real and present danger, fine. We need words to name the evil among us here and now. You’re being too delicate.”

Now translate that temporal bigotry into terms that are geographical, racial, or religious. “Middle Eastern savagery”? “Arab barbarism”? “Muslim brutality”? No, too many people get caught in the net if we cast it too widely. It’s unfair to them, obviously, but also unfair to ourselves in our effort to say exactly what we mean, not more than we mean.