This term refers to the size of bits the drill will accommodate.
Your other major decision with your power drill is chuck size. This term refers to the size of bits the drill will accommodate. Do you go with the standard ⅜” or move up to heavy-duty ½”? Drills with the larger chuck size will cost more. But the larger diameter at the base of the bits also means greater durability. It can save you the hassle of a lot of broken drill bits.