trip ****
actuate
trigger **
activate *
set off *
spark off
spark **
trigger off
touch off

Some incident, at the meal table, for example, would be enough to spark one off.

It doesn't take much to spark off a war over there.

Is this article some sort of attempt to spark off a gender war?

Although these results turned out to be false, it sparked off intense interest around the world.

I'm going to pass on what you've told us to the rest of the team and see if it sparks off any ideas.

Two people who spark each other off into things they would never have done singly.

It only needs a few to spark off the whole thing again.

When the two men were a safe distance away, Mark sparked off the explosive.

The least thing can spark off violence, and caricature is never far away.

Light sparked off something close to the pillow, and she reached for it.