Influence or authority over something.

“The government has complete control over the situation.”

A separate group or subject in an experiment against which the results are compared where the primary variable is low or non-existent.

The method and means of governing the performance of any apparatus, machine or system, such as a lever, handle or button.

To exercise influence over; to suggest or dictate the behavior of.

“With a simple remote, he could control the toy truck.”

(construed with for) To design (an experiment) so that the effects of one or more variables are reduced or eliminated.