When someone(s) plants explosive devices at locations where there will be crowds, detonates them and, as a result, kills and maims dozens of people, that is terrorism.
Why? Because senseless death in such a dramatic fashion tends to scare the bejeesus out of people. When the explosions are seconds apart and within walking/visual distance of each other, there is no question that it is terrorism. The explosions were meant to kill and terrify.
The problem is that we have come to associate terrorism with scary brown skinned people with middle eastern names and have conveeeeeniently forgotten that before Al Qaeda, there was Timothy McVeigh. Now, unless people are starting to refer to McVeigh as a freedom fighter, we should remember that we once called him a terrorist.
So, while we wait to determine who set the explosives off, we shouldn’t be afraid to call it what it is: terrorism. And it’s just as likely to be homegrown as middle eastern. All you right wing whip kissing cowards can chill until we get to the bottom of this.