Activate (verb)

1. To make something active or operational.
2. To cause something to begin to work or function.

Origin:

Mid 19th century: from latin activus "active" (from agere "do") + -ate.

Examples:

1. The button activates the machine.
2. The remote activates the TV.
3. The medicine activates the immune system.
4. The code activates the software.
5. The switch activates the lights.