tremor


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]