For the United States and its partners in the West, there is no doubt the Islamic State militants who have seized swathes of Iraq and Syria count as terrorists.
For Syria’s President Bashar al-Assad, the “terrorists” are all the opponents of his government — armed and unarmed. They in turn have branded his regime a “terrorist state”.
Secessionists in eastern Ukraine, separatists in China’s restive Xinjiang region, student protesters in Venezuela — the terrorist label has been applied to them all.
Two centuries after the term first appeared and more than a decade after the September 11 attacks, however, a clear definition of a “terrorist” remains elusive.
“The term ‘terrorist’ has expanded to the point that it just means ‘my enemy’,” said Marc Sageman, an ex-CIA agent, psychiatrist and author.
“So we see things from our own perspective — if one of us: freedom fighter, if one of them: terrorist.”
The build-up to the expanded US campaign against IS has seen the word in heavy use.
US Secretary of State John Kerry last week spoke of a “major counter-terrorism operation” and French President Francois Hollande on Monday said “the fight of the Iraqis against terrorism is our fight as well”.
In Tehran, deputy foreign minister Hossein Amir-Abdollahian said it was the Iraqi and Syrian governments who “have been engaged in a serious struggle against terrorism”, while a senior Assad adviser last week insisted that Syria had been the “victim” of terrorism since an anti-government uprising began in March 2011.
For Sarah Marsden, a lecturer at the University of Saint Andrews’ Handa Centre for the Study of Terrorism and Political Violence, the use of the word has grown increasingly “subjective”.
“That the UN has spent decades trying to reach agreement on a definition of terrorism reflects the deeply contested nature of the concept,” Marsden said.
The United Nations has been trying since 1972 to come up with a definition for terrorism and has passed 13 counter-terrorism conventions since 1996 without managing to do so.
The root of the problem, experts say, is that many groups are seen by some as terrorists but by others as engaging in a liberation struggle.