trembling -
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"
motion the act of changing location from one place to another; "police controlled the motion of the crowd"; "the movement of people from the farms to the cities"; "his move put him directly in my path"
tremolo vocal vibrato especially an excessive or poorly controlled one
