The Marshall Project is a nonprofit newsroom covering the U.S. criminal justice system. Sign up for our newsletters to receive all of our stories and analysis. Whatever the reason behind the worst mass shooting in modern American history, there is little debate about the facts: Stephen Paddock booked a room at the Mandalay in Las Vegas, ferried in an arsenal of weapons and ammo, and perched himself in a 32nd-floor window to shoot into an outdoor concert, killing 58 and wounding nearly 500. But it wasn’t an act of terrorism, authorities say. The reason, Clark County Sheriff Joseph Lombardo told reporters, was that, “we don’t know what his belief system was at this time.” As with other mass murders, the reluctance to label a white male a terrorist has sparked outrage from those who say no such benefit of the doubt would be extended to a Muslim or person of color. But Paddock’s beliefs do matter because of how terrorism is defined — or how it’s defined today. The FBI defines terrorism as “the unlawful use of force and violence against persons or property to intimidate or coerce a government ... in furtherance of political or social objectives.” The State Department uses similar language, and Merriam-Webster also invokes a political motivation — it was the word of the day Tuesday — defining it as “the use of violent acts to frighten ... as a way of trying to achieve a political goal.” Yet none of those is the end-all, be-all, says Maria Haberfeld, a professor of police science at John Jay College of Criminal Justice in New York. “There’s no agreed-upon definition,” she says. “It’s changed over the years so many times.” An earlier Webster’s volume, the Tenth Edition Collegiate Dictionary, copyright 1994, supports her assertion. The copy on my desk that formed my interpretation years ago defines it as “the systematic use of terror, esp. as a means of coercion.” A 2003 revision added the political angle, reading: “a systematic use of terror especially as a means of gaining some political end.” The more definitive Oxford English Dictionary includes both political and nonpolitical meanings, including “instilling of fear or terror; intimidation, coercion, bullying” and “spread[ing] a feeling of terror or alarm.” “Terrorist” has, at different points in history, conjured different feelings. A Latin root, terror cimbricus, derives from a Roman panic over an attack by the fierce Cimbri tribe, and conveys fear. Yet during the French Revolution, the period from which the word has had continuous use, Robespierre and his co-revolutionaries who presided over the Reign of Terror’s daily beheadings by guillotine proudly referred to themselves as terrorists. Only in more recent times has it morphed into a stark pejorative. Seeking to avoid that negative connotation, dueling sides in a conflict today will point a finger at each other as terrorists, says David Beard, a professor of rhetoric at the University of Minnesota Duluth. Beard also makes a distinction between the potentially temporary nature of politically motivated terrorism, which might cease once a goal has been achieved, as opposed to the unknown aspect of random acts of violence. “That was part of the thinking behind Palestinian acts of terrorism, to convince Israelis that you can't just get on a bus, you can’t just go to a cafe” — until there’s a Palestinian state, he says. A mass shooting for no discernible reason has no apparent end game, no statute of limitations. “That’s scarier,” Beard says. Further examples of the differing definitions cited by Haberfeld are in state laws, including Nevada, where despite Sheriff Lombardo’s contention about Paddock’s beliefs, political motivation is not prerequisite. The specific law, NRS 202.4415, defines an act of terrorism as “any act that involves the use or attempted use of sabotage, coercion or violence which is intended to … cause great bodily harm or death to the general population; or … cause substantial destruction…” Likewise, many states have statutes criminalizing “making terroristic threats,” as well as acting on them, without regard to motivation. Rather than specifying a specific motivation on which to bestow the mantle of terrorism, Haberfeld says it’s important to understand simply that a terrorist has one. “Terrorists can be defined as individuals who have some sort of a grievance against the larger society,” she writes in her book, “A New Understanding of Terrorism.” “It is a battle of the have-nots versus haves and their weapon is fear.” Las Vegas qualifies for that. “It was a classic terrorist event. There's no doubt in my mind,” she says, even if the relatively well-off Paddock did not initially appear to fit the profile of a “have-not.” “This guy was rich, and so was Osama bin Laden. It’s not about money. It’s about something out there that is missing, some sort of grievance against the larger society, and therefore [he has to] punish the larger society.” What Paddock’s missing piece was, we may never know. (He left a note, contents not yet made public.) But we all know too well now that an outdoor concert can become an unquestionable, and nightmarish, terrorist event. Robin Washington spent many years as a daily newspaper editor and writes frequently about civil rights and criminal justice. He may be reached at email@example.com or via Twitter @robinbirk.