The word comes from Ancient Greek θίξις thixis touch (from thinganein to touch) and -tropy, -tropous, from Ancient Greek -τρόπος -tropos of turning, from τρόπος tropos a turn, from τρέπειν trepein, to turn. Hence, it can be translated as something that turns (or changes) when touched.  It was invented by Herbert Freundlich originally for a sol-gel transformation.