A slingshot is a small toy or weapon that you can use for "shooting" stones. You might take aim at some old metal cans on a wall, knocking them off one by one with your slingshot.
A slingshot works like a small catapult, with rubber strips holding a pocket where the stone or other projectile sits. When you pull the pocket back and release it, the stone is projected forward. Slingshots are simple in design, but they're relatively modern inventions that rely on rubber, which was invented in 1839. The earliest use of slingshots was mainly by young troublemakers. The ammunition in a slingshot is sometimes referred to as a sling-stone.