Cotton drill is a strong cotton fabric woven in a twill weave to create a strong diagonal pattern in the weave. To give you an idea of this, traditional denim is a twill weave. What makes the weave so strong and why is it so good? The diagonal structure of the weave gives it its strength, and makes it tear resistant. Hence its usefulness for utility and work wear and uniform fabrics. A drill fabric is also a breathable material making it comfortable to wear, as it is 100% cotton. You can find cotton twill fabrics in home furnishings too.