"I think you need to open up a dictionary and see what the definition of terror is:"
Why? The word in question was terrorism, not terror. They have six letters in common, but they're not the same word.
(To be very clear: not everything that causes terror is terrorism. Otherwise we'd be struggling to cope with a prison population which had suddenly swollen to include all the world's horror movie directors (at least, the good ones) and haunted house operators.)