To Activate

1. (transitive) To encourage development or induce increased activity; to stimulate.
2. (transitive) To put a device, mechanism (alarm etc.) or system into action or motion; to trigger, to actuate, to set off, to enable.
3. (transitive, chemistry, physics) To render more reactive; excite.
4. (transitive, biology) To render a molecule reactive, active, or effective in performing its function.
5. (transitive, physics) To render a substance radioactive.
6. (transitive, chemistry) To hasten a chemical reaction, especially by heating.
7. (transitive, computing, software) To remove the limitations of demoware by providing a license; to unlock.
8. (transitive) To aerate in order to aid decomposition of organic matter.
9. (transitive, military) To organize or create a military unit or station.
10. (transitive, sports) To bring a player back after an injury.

actuate

enable

get going

set going

set in motion

set off

spur

start

stimulate

trigger

turn on

deactivate

inactivate