Dictionary.net

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"

Involuntary contraction or twitching of the muscles. It is a physiologic method of heat production in man and other mammals.

n. The act of breaking or dashing to fragments; severance; a trembling or shaking from cold or dread of danger.