In baseball a chopper is a ball hit into the dirt surrounding home plate, or a ball that bounces many times before being picked up by the defense. In the first case, a ball hit into the dirt surrounding home plate will usually bounce high into the air. The harder the ball is hit, the greater chance it has of reaching the infield defense while still airborne, which will usually lead to an easy out. If the ball is hit close to the ground but bounces outside the dirt immediately surrounding home plate, it will typically lead to more bounces which puts it on a path that may be difficult to predict for the defense. These hits are some of the hardest to field due to their unpredictability.
In baseball, the goal of the hitter is to get on base or score, and the most direct way to accomplish the former is to hit the ball. Professional baseball players will often try to place the ball or hit the ball a certain way in order to increase their chances of getting on base. A chopper is one of the types of hits hitters like because it removes the ability for the defense to catch the ball in the air, and it adds a degree of difficulty to fielding the ball. The term "chopper" comes from the path the ball takes. Since it bounces at least once and usually takes a path that is difficult to predict, its path is considered "choppy".