Mortar is like a special kind of gun that shoots bombs in the air. Imagine playing catch with your friend by throwing a ball, but instead of a ball, mortar throws big bombs that go BOOM! BOOM! BOOM! They're really powerful and go high up into the sky before they come back down and explode on the ground to make a big BOOM! sound. Soldiers use mortars to protect themselves during battles, but they have to be very careful because they can be dangerous if not used the right way.