In its broadest sense, terrorism is any act designed to cause terror.
"Terrorism" comes from the French word terrorisme, and originally referred specifically to state terrorism as practiced by the French government during the 1793–1794 Reign of Terror. The French word terrorisme in turn derives from the Latin verb terrere (e, terreo) meaning "to frighten".
In November 2004, a Secretary-General of the United Nations report described terrorism as any act "intended to cause death or serious bodily harm to civilians or non-combatants with the purpose of intimidating a population or compelling a government or an international organization to do or abstain from doing any act"
the United Nations General Assembly has repeatedly condemned terrorist acts using the following political description of terrorism: Criminal acts intended or calculated to provoke a state of terror in the public, a group of persons or particular persons for political purposes are in any circumstance unjustifiable, whatever the considerations of a political, philosophical, ideological, racial, ethnic, religious or any other nature that may be invoked to justify them.
U.S. Code Title 22 Chapter 38, Section 2656f(d) defines terrorism as: “Premeditated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents, usually intended to influence an audience.”
By distinguishing terrorists from other types of criminals and terrorism from other forms of crime, we come to appreciate that terrorism is :
- ineluctably political in aims and motives;
- violent—or, equally important, threatens violence;
- designed to have far-reaching psychological repercussions beyond the immediate victim or target;
- conducted either by an organization with an identifiable chain of command or conspiratorial cell structure (whose members wear no uniform or identifying insignia) or by individuals or a small collection of individuals directly influenced, motivated, or inspired by the ideological aims or example of some existent terrorist movement and/or its leaders; and
- perpetrated by a subnational group or nonstate entity.
A definition proposed by Carsten Bockstette at the George C. Marshall European Center for Security Studies, underlines the psychological and tactical aspects of terrorism:
Terrorism is defined as political violence in an asymmetrical conflict that is designed to induce terror and psychic fear (sometimes indiscriminate) through the violent victimization and destruction of noncombatant targets (sometimes iconic symbols). Such acts are meant to send a message from an illicit clandestine organization. The purpose of terrorism is to exploit the media in order to achieve maximum attainable publicity as an amplifying force multiplier in order to influence the targeted audience(s) in order to reach short- and midterm political goals and/or desired long-term end states.