n A separate group or subject in an experiment against which the results are compared where the primary variable is low or nonexistence.
n The method and means of governing the performance of any apparatus, machine or system, such as a lever, handle or button.
n A security mechanism, policy, or procedure that can counter system attack, reduce risks, and resolve vulnerabilities; a safeguard or countermeasure.
n (context|project management) A means of monitoring for, and triggering intervenion in, activities that are not going according to plan.
n (graphical user interface) An interface element that a computer user interacts with, such as a window or a text box.