tremor (
http://definr.com/tremor)
n 1: an involuntary vibration (as if from illness or fear) [syn:
shudder]
2: a small earthquake [syn:
earth tremor,
microseism]
3: shaking or trembling (usually resulting from weakness or
stress or disease)
v : shake with seismic vibrations, as of planets; "The earth was
quaking" [syn:
quake]