Cotter drill

Drill 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. [1913 Webster]

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. [1913 Webster]

3. Any exercise, physical or mental, enforced with regularity and by constant repetition; as, a severe drill in Latin grammar. [1913 Webster]

4. (Zo["o]l.) 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}. [1913 Webster]

{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. [1913 Webster]