These divergences have made it impossible for the United Nations to conclude a Comprehensive Convention on International Terrorism that incorporates a single, all-encompassing, legally binding, criminal law definition of terrorism. The international community has adopted a series of sectoral conventions that define and criminalize various types of terrorist activities. Since 1994, 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. law
Various legal systems and government agencies use different definitions of terrorism in their national legislation. 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".18 U.S.C.
Terrorism, in its broadest sense, is the use of criminal violence to provoke a state of terror or fear, mostly with the intention to achieve political or religious aims. The term is used in this regard primarily to refer to intentional violence during peacetime or in the context of war against non-combatants (mostly civilians and neutral military personnel). The terms "terrorist" and "terrorism" originated during the French Revolution of the late 18th century but became widely used internationally and gained worldwide attention in the 1970s during the Troubles in Northern Ireland, the Basque conflict, and the Israeli–Palestinian conflict. The increased use of suicide attacks from the 1980s onwards was typified by the 2001 September 11 attacks in the United States. There are various different definitions of terrorism, with no universal agreement about it. Terrorism is a charged term. It is often used with the connotation of something that is "morally wrong". Governments and non-state groups use the term to abuse or denounce opposing groups. Varied political organizations have been accused of using terrorism to achieve their objectives. These include left-wing and right-wing political organizations, nationalist groups, religious groups, revolutionaries and ruling governments. Legislation declaring terrorism a crime has been adopted in many states. When terrorism is perpetrated by nation states, it is not considered terrorism by the state conducting it, making legality a largely grey-area issue.