What is 'terrorism'? Boston bombings renew efforts to define pain, motives in a single word

The definition of terrorism is being discussed again as the United States waits for a motive in the Boston Marathon bombing.

Experts — and the dictionary — define terrorism as the use of violence and fear to pursue political goals. There's no word yet about any motivation for the explosions Monday that killed three people and maimed scores more.

President Barack Obama didn't use the word when he spoke hours after the attack. By Tuesday, he called it an "act of terror" any time bombs are used to target innocent civilians.

That definition works for people like Jay Winuk (WIN'-uk), who lost a brother on 9/11. Others are holding back, like some history students at Kent Place School in New Jersey. They want more information before deciding what to call the Boston tragedy.