The story
From the group's former Arabic-language name, الدَّوْلَة الْإِسْلَامِيَّة فِي الْعِرَاق (ad-dawla l-ʔislāmiyya fī l-ʕirāq, literally “the Islamic State in Iraq”).
Etymology from Wiktionary, CC BY-SA 4.0.
Islamic State in Iraq
Today it means: ISIL/ISIS/Islamic State Full definition →