D defs.my
Entry 1 sense Webster, 1913

Tropism

/(trō"pĭz'm)/ · Tro·pism · IPA /ˈtɹoʊˌpɪzəm/
01 n. Modification of the direction of growth, caused by some external influence, such as light; -- sometimes used for motion of an organism towa…
  1. 1.
    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.(Physiol.)