Drill is a strong, durable cotton fabric with a strong bias (diagonal) in the weave. It can be used unbleached, although it is more often bleached or dyed.
The lighter weights are used in such clothing items as shirts, safari jackets, blouses, playwear, and martial arts wear.
Khaki drill is made into uniforms; boatsail drill is made into sails for sailing craft and is unbleached; drill is also made into pocket linings.