Definition of CONTROL

1 Archaic: to check, test, or verify by evidence or experiments b: to incorporate suitable controls in . A control is a duplicate setup of the experiment you are performing with everything identical except for the variable that you are testing.

Or, it is how the experiment would happen naturally, without you doing anything. For example, if you are testing the effects of a certain medication on humans, you give half of the subjects the medication and the other half a placebo, which is a sugar pill that has no effect. The latter group is the "control group". Their purpose is to remove the psychological effect of taking the medication from the results of the experiment, so that the only variable remaining is the actual effects of the medication.

Constants are things that are kept the same for all trials, like making sure that every subject is taking a pill (and that they believe it is the medication in question, even if it is only a placebo).

2 a: to exercise restraining or directing influence over: regulate b: to have power over : rule c: to reduce the incidence or severity of especially to innocuous levels

Intransitive verb : to incorporate controls in an experiment or study —used with for

Examples:

The small boy could not control the big dog.
The parents could not control their child.
Her family controls the business.
The police controlled the crowd.
One country controls the whole island.
A thermostat controls the room's temperature.
The lights on stage are controlled by this computer.
He controlled the volume by turning the radio's knob.
She struggled to control the cart as it rolled before her down the steep, bumpy road.
The rebel army now controls nearly half the country.

Origin of CONTROL; FIRST KNOWN USE:....15th century

Middle English countrollen, from Anglo-French contrerouler, from contreroule copy of an account, audit, from Medieval Latin contrarotulus, from Latin contra- + Medieval Latin rotulus roll — more at roll

Synonyms: bridle, check, constrain, contain, curb, govern, hold, inhibit, keep, measure, pull in, regulate, rein (in), reign, restrain, rule, tame

Antonyms: lose