v.
 shake involuntarily, typically as a result of anxiety, excitement, or frailty. 
▸be in a state of extreme apprehension.
 ▸(of a thing) shake or quiver slightly.
n.
 a trembling feeling, movement, or sound.
 
  Phrase
  
    
      - all of a tremble
 informal extremely agitated or excited. 
    
   
  Derivative
  
    - trembling adj.
  - tremblingly adv.
  - trembly adj. (informal).
 
   
  Etymology
  ME: from OFr. trembler, from med. L. tremulare, from L. tremulus (see tremulous).