Qua·ver, v. i. [imp. & p. p. Quavered p. pr. & vb. n. Quavering.]
  1. To tremble; to vibrate; to shake.
  2. Especially, to shake the voice; to utter or form sound with rapid or tremulous vibrations, as in singing; also, to trill on a musical instrument
  quavering
       adj : (of the voice) quivering as from weakness or fear; "the old
             lady's quavering voice"; "spoke timidly in a tremulous
             voice" [syn: tremulous]