thig·mo·tax·is 
(thĭg′mə-tăksĭs)
(thĭg′mə-tăksĭs)n.
Movement of an organism in response to contact with a solid body.
[Greek thigma, touch (from thinganein, to touch; see dheigh- in the Appendix of Indo-European roots) + -TAXIS.]
thig′mo·tactic (-tăktĭk) adj.