On the eve of President Barack Obama's speech outlining Washington's strategy against the group, in which he will likely refer to it as ISIL, we ask: What's in a name?
It all started in 2004 when the late Abu Musab al-Zarqawi formed an al Qaeda splinter group in Iraq. Within two years, al-Zarqawi's al Qaeda in Iraq was trying to fuel a sectarian war against the majority Shiite community.
In June 2006, al-Zarqawi was killed in a U.S. strike. Abu Ayyub al-Masri, his successor, several months later announced the creation of the Islamic State in Iraq (ISI).
In April 2013, Islamic State in Iraq absorbed the al Qaeda-backed militant group in Syria, Jabhat al-Nusra, also known as the al-Nusra Front. Its leader Abu Bakr al-Baghdadi said his group will now be known as Islamic State in Iraq and the Levant. Since then, the English-speaking world seems to have had a hard time settling on a name for them.
President Obama, the United Nations and some news organizations refer to the jihadist group by the acronym ISIL, which stands for Islamic State in Iraq and the Levant.
CNN Global Affairs Correspondent Elise Labott said the U.S. has stuck with ISIL because the group appears to have to set it sights beyond Iraq and Syria. And also because Washington doesn't want to recognize their plans for a caliphate.
CNN national security analyst Peter Bergen believes ISIL is a more accurate translation of the group's name.
The 'L' stands for Levant which is a translation of "al-Sham" -- the word the group uses to refer to itself, Bergen said.
"But the Levant is a relatively obscure word in English -- in English, we refer to Syria. Of course, the Levant is larger than Syria," Bergen said.
"We believe this is the most accurate translation of the group's name and reflects its aspirations to rule over a broad swath of the Middle East," said John Daniszewski, vice president and senior managing editor for international news for The Associated Press
, according to an AP blog post
Al-Sham is a reference to a region that stretches from Turkey through Syria to Egypt and includes the Palestinian territories, Jordan and Lebanon, according to Rashid Khalidi, a Columbia University professor and expert on Syrian history.
Part of the confusion stems from the fact that al-Sham has many meanings in Arabic.
Khalidi said: "How you translate 'al-Sham' determines whether you have an 'L' or an 'S' in English. It's the same word in Arabic. How you translate the term into English determines if you're of the 'ISIL' camp or the 'ISIS' camp. The Levant, which can extend from northern Egypt to Greece, is not as precise."
On the United States government's use of ISIL, Khalidi surmised: "Maybe because you don't want to give the dignity of the name that they give themselves."
Nawaf Obaid, a visiting fellow at the Belfer Center for Science and International Affairs at Harvard University, said via email that ISIL is preferable in English "to make it clear to a Western audience."
Levant denotes Syria and Lebanon in Arabic, "so better to stick to ISIL and clarify that it's the same as ISIS, but a more accurate translation from the Arabic," he said.
ISIS is an English translation of the acronym in Arabic for Al-Dawla Al-Islamiya fi al-Iraq wa al-Sham, or the Islamic State in Iraq and al-Sham.
The organization has said its goal is to form an Islamic state, or caliphate, over the entire region, stretching from Turkey through Syria to Egypt and including the Palestinian territories, Jordan and Lebanon.
Some think ISIS flows better as a word in English. It also happens to be the name of one of a goddess of ancient Egypt.
CNN has been referring to the organization as ISIS, shorthand for the Islamic State in Iraq and Syria.
Arabic speakers say al-Sham can be translated to mean the Levant, Syria, greater Syria, and even Damascus.
The jihadists like to refer to themselves simply as the Islamic State, a term more accurately reflecting the organization's aspirations of creating a caliphate across national borders.
They prefer to be known either as the Islamic State -- al-Dawla al-Islamiya in Arabic -- or just the State, al-Dawla. That is what they call themselves in online videos.
Finally, a lesser-known acronym to Western readers: DAIISH. It is the straight Arabic shorthand for the group known as: al-Dawla al-Islamiya fi Iraq wa al-Sham, commonly used in the Arab world and among many Arab media outlets and politicians.
When people in the Arab world, use the term DAIISH, it's derogatory, according to Columbia's Khalidi.
"Those who disagree with them, call them DAIISH," Khalidi said, adding that the jihadists have objected to the name.