Synonyms for Trembling (same or very similar meaning)
WordNet sense 1 (a shaky motion):
palpitation, quiver, shakiness, vibration, quivering, shakingWordNet sense 2 (vibrating slightly and irregularly; as e.g. with fear or cold or like the leaves of an aspen in a breeze):
shaky, shiveringFrom the ODE community, based on WordNetadd/edit