The Collaborative International Dictionary of English v.0.48:

Tremulous \Trem"u*lous\, a. [L. tremulus, fr. tremere to
   tremble. See Tremble.]
   1. Shaking; shivering; quivering; as, a tremulous limb; a
      tremulous motion of the hand or the lips; the tremulous
      leaf of the poplar.
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   2. Affected with fear or timidity; trembling.
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            The tender, tremulous Christian.      --Dr. H. More.
      [1913 Webster] -- Trem"u*lous*ly, adv. --
      Trem"u*lous*ness, n.
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