1 - Influence or authority over something.
2 - A separate group or subject in an experiment against which the results are compared where the primary variable is low or non-existent.
3 - The method and means of governing the performance of any apparatus, machine or system, such as a lever, handle or button.
1 - To exercise influence over; to suggest or dictate the behavior of.
2 - (construed with for) To design (an experiment) so that the effects of one or more variables are reduced or eliminated.





