Addressing the National Assembly, Mr. Fabius declared that the Islamic State’s claim to represent a caliphate — a state governed by Islamic principles — in Syria and Iraq was geopolitically and linguistically false.

“This is a terrorist group and not a state,” he said. "I do not recommend using the term Islamic State because it blurs the lines between Islam, Muslims and Islamists.” Calling on news organizations to follow his lead, he added, “The Arabs call it Daesh, and I will be calling them the Daesh Cutthroats.”

The term Daesh — also sometimes referred to as Da’ish — is an acronym of the group’s Arabic name, Al-Dawla al-Islamiya fi al-Iraq wa al-Sham, according to Aymenn Jawad al-Tamimi, who studies the Islamic State and is now a researcher with the Interdisciplinary Center in Herzliya, Israel. It is also used without being meant as an insult.

But, Mr. Tamimi said, the acronym has also been embraced by critics of the group, as the word could have negative connotations in the Arab world, since it is close to the word daes, meaning to tread underfoot, trample or crush. (Several residents of Mosul, Iraq, which fell to the Islamic State in June, told The Associated Press that the Sunni militant group was so incensed about the use of the term Daesh that members threatened to cut off the tongues of anyone who uttered it.)

In the United States, Nihad Awad, executive director of the Council on American-Islamic Relations, based in Washington, said his group had settled on ISIS, though he personally referred to the group as “Daesh — though sometimes I say ‘the Evil State.’ ” Because of its similarity to daes, he explained, “it doesn’t sound good.”

Several representatives of American Islamic associations said that any of the names used for the group were acceptable so long as they did not include the term Islamic. Salam al-Marayati, president of the Muslim Public Affairs Council, based in Los Angeles, said his group had stuck with the acronym ISIS “because we believe by using Islam in any description of these groups, it’s exactly what they want — a religious validation of what they’re doing.”