Source : Webster's Revised Unabridged Dictionary (1913)

Quake \Quake\, v. i. [imp. & p. p. {Quaked}; p. pr. & vb. n.
   {Quaking}.] [AS. cwacian; cf. G. quackeln. Cf. {Quagmire}.]
   1. To be agitated with quick, short motions continually
      repeated; to shake with fear, cold, etc.; to shudder; to
      tremble. ``Quaking for dread.'' --Chaucer.

            She stood quaking like the partridge on which the
            hawk is ready to seize.               --Sir P.
                                                  Sidney.

   2. To shake, vibrate, or quiver, either from not being solid,
      as soft, wet land, or from violent convulsion of any kind;
      as, the earth quakes; the mountains quake. `` Over quaking
      bogs.'' --Macaulay.

Quaking \Quak"ing\,
   a. & n. from {Quake}, v.

   {Quaking aspen} (Bot.), an American species of poplar
      ({Populus tremuloides}), the leaves of which tremble in
      the lightest breeze. It much resembles the European aspen.
      See {Aspen}.

Source : WordNet®

quaking
     adj : vibrating slightly and irregularly; as e.g. with fear or
           cold or like the leaves of an aspen in a breeze; "a
           quaking bog"; "the quaking child asked for more";
           "quivering leaves of a poplar tree"; "with shaking
           knees"; "seemed shaky on her feet"; "sparkling light
           from the shivering crystals of the chandelier";
           "trembling hands" [syn: {quivering}, {shaking}, {shaky},
            {shivering}, {trembling}]