vibration

vibration (http://definr.com/vibration)

     n 1: the act of vibrating [syn: quiver, quivering]
     2: a shaky motion; "the shaking of his fingers as he lit his
        pipe" [syn: shaking, shakiness, trembling, quiver,
         quivering, palpitation]
     3: (physics) a regular variation in value about a mean [syn: oscillation]