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

I don't know what movement of his, if any, triggered off that reaction in me.

Or he had not been until this moment; now something seemed to have triggered him off.

They will be less likely to trigger off more spots.

He triggered off a second shot as all three men turned toward the sound of his gun.

I wanted to call my son back, tell him to leave Andrew alone, but that would have triggered off too many questions.

"What in the name of space science triggered it off?"

Triggered off by the sight of the carriers, the situation?

But two of them triggered off their C-802s just in time.

For, in a manner still not understood, the little man did trigger it off.

Simply walking down the street can trigger off ideas about society.