A drill is a power tool that's used for making narrow holes or sometimes for pushing screws into wood or other hard material. The word is also a verb to describe the action a drill performs. For example, a dentist might drill into your tooth if you have a cavity.
A carpenter's drill can be held in one hand, while an oil drill is a large rig that hollows out holes in rock through which oil can flow. To drill is to bore holes in a hard surface, and it's also to teach something by repeating facts over and over: "I hate math, because my teacher just drills multiplication tables." Drill has a Dutch root, drillen, "to bore a hole, turn around, or whirl."