Terrorism can describe the slaughter of a village, the bombing of a cinema, buildings crumbling, planes being hijacked or the hacking of a database for destructive purposes.
It can be used as a call to action, a rationale for retribution, a cheap shot against an opponent or a gross hyperbole uttered for political gain. Recent events have moved many people to reevaluate their definition of terrorism, while others have simply become desensitized by its overusage in media and everyday conversation.
The term was coined in the 18th century during the French Reign of Terror, when average citizens were often publically executed to scare others into submission. Terrorism as an act, however, is much older than that. Murders, assasinations, the burning of villages and the rape of countrywomen were all on record long before old Robespierre ever went mad with power. Violence has been part of our history as long as we've had a history; terrorism has been a part of that history for as long as we've had politics.
In 1937, the League of Nations decreed that "all criminal acts directed against a State intended or calculated to create a state of terror in the minds of particular persons or persons in the general public" were to be considered terrorism.
Britain's Terrorism Act 2000 defines terrorism as "the use or threat of action to influence a government or intimidate the public for a political, religious or ideological cause. The action involved includes serious violence against people or danger to life, a serious risk to public health or safety, or serious damage to property."
The U.S. Department of Defense prefers to define terrorism as "the calculated use of violence or the threat of violence to inculcate fear; intended to coerce or to intimidate governments or societies in the pursuit of goals that are generally political, religious, or ideological."
The consensus seems to be that terrorism is unlawful violence (as in, not sanctioned by war) that incites terror among civilians. This terror disables or alters the civilians' way of life for a political purpose. It is action that is premeditated, deliberate and designed to create the largest disruption with the smallest amount of force.
Groups who are not backed by dominant military powers are more likely to use terrorism, because their lack of resources and manpower makes traditional warfare all but impossible. Frequently, however, these groups are labeled as terrorist simply because they are in the minority. The difference between resistance and terrorism is a slight one, often highlighted by value judgments and prejudice. And while it is true that "one man's terrorist is another man's freedom fighter," the largest distinction appears to be target. Aiming for your enemy is acceptable, aiming for your enemy's wife and children is not. For some of us, the distinction is of little consolation but the effect is quite visible. When soldiers die in war, we grow angry but do not feel endangered ourselves. When terrorism occurs, there is the inescapable fear that we may be next.
There is much controversy over the recent War on Terrorism, as many people believe it is being waged by a country that may frequently engage in acts of terrorism for its own gain. Furthermore, waging war against a concept that violates principles of war seems awkward at best. How can you fight a battle against someone whose goal is to win without combat?
These are complicated times in which we live, where it is difficult to distinguish between right and wrong, good and bad and missions of war or peace. Definitions in pristine doctrines kept in buildings far away from the bloodshed and the fear seem unlikely solace. Maybe it helps, though, to have a name for what you're dealing with.
Sources
http://www.crf-usa.org/terror/What_Is_Terrorism_rev.htm
http://news.bbc.co.uk/1/hi/world/americas/1555265.stm
http://www.terrorismanswers.com/terrorism/introduction.html
Many thanks to the wonderful, the talented, the oddly misshapen Cletus the Foetus.