tremble (
http://definr.com/tremble)
n : reflex shaking caused by cold or fear or excitement [syn:
shiver,
shake]
v 1: move with or as if with a tremor; "his hands shook"; "My
legs trembled when I went onstage" [syn:
shake,
didder]
2: move or jerk quickly and involuntarily up and down or
sideways; "His hands were trembling when he signed the
document"