Republican presidential nominee Donald Trump has repeatedly criticized President Obama for refusing to use the phrase "radical Islam." But what do those words actually mean? (Peter Stevenson/The Washington Post)

Donald Trump has so far been vague on his strategy for dealing with the Islamic State. For some time, he promised he had a secret strategy in his back pocket that would defeat them (although this week, he seemed to suggest he would look to the generals for a plan.) A central part of his pitch to voters is that the Obama administration has been negligent in dealing with the Islamic State. And, echoing a longtime conservative critique, Trump says that a big part of the problem is President Obama's refusal to use certain specific phrases to describe the group — "radical Islam" and "radical Islamic terrorism."

Obama has long insisted that using those exact words won't help defeat the Islamic State. Instead, he turns to more nuanced phrases (like ISIL, which stands for the Islamic State in Iraq and the Levant, rather than ISIS, which refers to the group's presence in Iraq and Syria.) The use of those words, he says, helps assure Muslims in the United States and around the world that the war on terror is being fought not only by the West but also by Muslims across the Middle East, especially in Iraq and Syria.

Clearly, word choice does matter to people on both sides of the argument. So I reached out to Shadi Hamid, a senior fellow at the Brookings Institution and author of "Islamic Exceptionalism: How the Struggle Over Islam is Reshaping the World", to see what I could learn what Trump's preferred phrasing of "radical Islam" actually means to various groups, including Muslims, Trump supporters and detractors. An excerpt from our conversation at Hamid's office in Washington is below.

THE FIX: Donald Trump seems pretty set on using the phrase "radical Islam" and insists that President Obama should use it, too. But Obama pushes back against that, and says it's really a semantic argument that won't help defeat terrorists. Why are those specific words a source of controversy?

Shadi Hamid: I think it's absurd that we're having a national conversation over, in what order do you arrange the words to describe something that we all agree is bad, right? So I think that Trump and others have distracted from the key issue at hand, which is how to fight terror more effectively.

By putting "radical" in front of the word "Islam," it's almost making a suggestion that "radical" and "Islam" go together, you're matching these two words, and it can also connote this idea of Islam being inherently radical. It seems that you're targeting the entire religion if you are putting "radical" and "Islam" next to each other.

FIX: And the other side says that they are more sensitive to the way those two words actually come across.

HamidThere's no need to use "radical Islam" when there are so many other things you could use that still do capture the religious dimension. So you could use "radical Islamism." You could use "radical jihadism," "Salafi jihadism," whatever it might be. So there are options that are more precise.

But I think there's something else going on here, and it's that using this phrase, "radical Islam," has almost become a stand-in for anti-Muslim bigotry. Trump has invested these words with new meaning, regardless of what they may have meant four or five years ago. So in that sense, Trump is correct — words do matter, and we should be concerned that he's using these words as a kind of dog whistle that really feeds into the anti-Muslim bigotry that is unfortunately becoming more prevalent in the U.S. …

Our conversation continues in the video above.