tro·pism /ˈtroˌpɪzəm/
  向性,趨性,屈性
  tro·pism /ˈtroˌpɪzəm/ 名詞
  向性,趨向性
  Tro·pism n.  Physiol. Modification of the direction of growth, caused by some external influence, such as light; -- sometimes used for motion of an organism toward or away from an external stimulus, more properly called taxis.
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  tropism
       n : an involuntary orienting response; positive or negative
           reaction to a stimulus source