vt,
1. to make something happen
1a. to cause someone to have particular feelings or memories
1b. to cause someone to do or say something
2. to make a machine or piece of equipment start to work
n,
1. the part of a gun that you move with your finger to make the gun fire
2. something that produces an immediate result
ex)
Further violence was triggered by news of his death.
You find that strangely familiar smells trigger memories of childhood.
The report has triggered a fierce response from the governor.
A sensor had triggered the security camera.
She lifts her gun and pulls the trigger.
It was the trigger for a whole new investigation.