The word terrorism has been abused and misunderstood for so long it almost fails to have any meaning. Terrorism is (according to dictionary.com):
the use of violence and threats to intimidate or coerce, esp. for political purposes.
the state of fear and submission produced by terrorism or terrorization.
a terroristic method of governing or of resisting a government.
That being said, I am sad to report the the United States of America is the largest Terrorist State in the world (by definition) and will remain so untill both of our illegal wars have ended.