activate
v.v. to make something start working or to turn a system on. You often use this for machines, alarms, or processes in your body.
v. to cause a device, process, or chemical reaction to begin functioning. Transitive — requires a direct object such as a mechanism, account, or biological pathway.
You need to enter a code to activate the alarm.
The bank sent a new credit card, but I have to call them to activate it before use.
Specialized white blood cells circulate in a dormant state until they encounter specific pathogens that activate their defensive response, triggering a cascade of immune activity throughout the body.
From active + -ate.
The verb is transitive and takes a direct object. In technical contexts, it is frequently used in the passive voice ('the system was activated').