To move to and fro in short, jerky movements
To move to and fro violently
A state of nervous restlessness or agitation.
"I can't watch this," she said, a tremble in her voice.
I tremble to write these following lines.
It makes me tremble!
It still rained, but it wasn't cold that made her hands tremble as she left the car.
Why do his legs tremble under him as he walks, leaning upon a stick?