Drill, n.
 1. An instrument with an edged or pointed end used for making holes in hard substances; strictly, a tool that cuts with its end, by revolving, as in drilling metals, or by a succession of blows, as in drilling stone; also, a drill press.
 2. Mil. The act or exercise of training soldiers in the military art, as in the manual of arms, in the execution of evolutions, and the like; hence, diligent and strict instruction and exercise in the rudiments and methods of any business; a kind or method of military exercises; as, infantry drill; battalion drill; artillery drill.
 3. Any exercise, physical or mental, enforced with regularity and by constant repetition; as, a severe drill in Latin grammar.
 4. Zool. A marine gastropod, of several species, which kills oysters and other bivalves by drilling holes through the shell. The most destructive kind is Urosalpinx cinerea.
 Bow drill, Breast drill. See under Bow, Breast.
 Cotter drill, or Traverse drill, a machine tool for drilling slots.
 Diamond drill. See under Diamond.
 Drill jig. See under Jig.
 Drill pin, the pin in a lock which enters the hollow stem of the key.
 Drill sergeant Mil., a noncommissioned officer whose office it is to instruct soldiers as to their duties, and to train them to military exercises and evolutions.
 Vertical drill, a drill press.