Drill is a tool that spins rapidly to bore holes into wood, metal, plastic, or other materials. A drill has a sharp bit at the end that cuts into the material as it rotates, creating a clean hole where you need one. Carpenters use drills to make holes for screws when building furniture. Dentists use tiny drills to remove decay from teeth.

The word also means practicing something repeatedly until you can do it automatically. When basketball players run shooting drills, they practice the same shot over and over until their muscles remember the motion. Students do multiplication drills to memorize their times tables. Fire drills help everyone practice evacuating a building quickly and calmly so they'll know exactly what to do in an emergency.

A drill sergeant is a military instructor known for making soldiers practice marching, exercises, and other skills repeatedly. The connection between these meanings is repetition: just as a drill spins around and around to cut through material, practice drills repeat the same action again and again to make it second nature. When something is drilled into your head, you've heard or practiced it so many times that you won't forget it.