President Barack Obama speaks about the U.S. fight against the Islamic State group from the Oval Office of the White House, Sunday, Dec. 6, 2015. Reuters/Saul Loeb/Pool

In President Barack Obama’s speech addressing the nation on terrorism Sunday evening, he referred to the Islamic State group as “ISIL” rather than the more commonly used “ISIS.” It’s the administration's habit and one that has occasionally confounded Americans and garnered some criticism since the extremist group began seizing territory in June 2014.

“We will destroy ISIL and any other organization that tries to harm us. Our success won’t depend on tough talk, or abandoning our values or giving into fear. That’s what groups like ISIL are hoping for,” the president said from the Oval Office.

The reason the Obama administration, and some others, have opted to call the group “ISIL” is partly geographical, partly grammatical. Whereas ISIS stands for “Islamic State of Iraq and Syria,” ISIL stands for “Islamic State of Iraq and the Levant,” meaning the whole eastern shore of the Mediterranean Sea. It includes Syria, Lebanon, Palestine, Israel and Jordan, and so is thought to more accurately describe the large region threatened by the group’s activities, the Washington Post wrote earlier this year.

Furthermore, the group’s name in Arabic is al-Dawla al-Islamiya fi al-Iraq wa al-Sham, and “Levant” is sometimes argued to be the more accurate translation for “al-Sham.”

Some politicians and media commentators, however, have claimed that Obama's use of the term "ISIL" demonstrates a reluctance to follow the group into Syria.

Debate has been raging for some time about what best to call the terrorist organization. Some world leaders, such as French President François Hollande, prefer to call it “Daesh,” an Arabic acronym that can double as an insult depending on how it is conjugated.

“Daesh” can mean “to trample down and crush” or “a bigot who imposes his view on others,” making the term a highly offensive one to the group, the Boston Globe reported. ISIS has threatened “to cut the tongue of anyone” caught publicly referring to it as Daesh.