Is it farther or further?
1900, from thigmo-, comb. form meaning "touch," from Greek thigma "touch" + tropism.
thigmotropism thig·mot·ro·pism (thĭg-mŏt'rə-pĭz'əm)n. The turning or bending response of an organism or part of an organism upon direct contact with a solid surface or object. Also called stereotropism.